diff --git a/.gitignore b/.gitignore
index be94685..54e454c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
-/plag
+/plageq
+/plagmax
 /*.o
diff --git a/Makefile b/Makefile
index 7a26ded..6339f12 100644
--- a/Makefile
+++ b/Makefile
@@ -1,13 +1,16 @@
 CC=gcc
 CFLAGS= -O3
 
-all: plag
+all: plagmax plageq
 
-plag: plag.c lib.o lib.h config.h
-	$(CC) $(CFLAGS) -o $@ plag.c lib.o
+plagmax: plagmax.c lib.o lib.h config.h
+	$(CC) $(CFLAGS) -o $@ plagmax.c lib.o
+
+plageq: plageq.c lib.o lib.h config.h
+	$(CC) $(CFLAGS) -o $@ plageq.c lib.o
 
 lib.o: lib.c lib.h
 	$(CC) $(CFLAGS) -o $@ -c lib.c
 
 clean:
-	rm plag lib.o
+	rm plagmax plageq lib.o
diff --git a/config.h b/config.h
index 43ab6e8..e44adaa 100644
--- a/config.h
+++ b/config.h
@@ -8,4 +8,6 @@
 typedef uint32_t pos_t;
 typedef int mask_t;
 
+#define STRICT_MAX_DEPTH 32 // less than 32 is aligned anyway
+
 #endif /* !CONFIG_H */
diff --git a/plageq.c b/plageq.c
new file mode 100644
index 0000000..f76dd90
--- /dev/null
+++ b/plageq.c
@@ -0,0 +1,219 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <error.h>
+#include <errno.h>
+
+#include "config.h"
+#include "lib.h"
+
+#define DEPTHB ((int)((STRICT_MAX_DEPTH)+7)/8)
+#define DEPTHL ((DEPTHB)*8)
+
+struct node {
+	pos_t a[2];
+	uint8_t b[DEPTHB];
+};
+typedef struct node *iptree;
+typedef void (*bitsfun)(bits, mask_t, mask_t, mask_t);
+
+pos_t maxpos = 0;
+
+void clearb(uint8_t *b) {
+	bzero(b, DEPTHB);
+}
+
+void setb(uint8_t *b, int n, int i) {
+	int p = n >> 3;
+	if (p >= DEPTHB) return;
+	if (i) {
+		b[p] |= 1 << (n & 0x7);
+	} else {
+		b[p] &= ~(1 << (n & 0x7));
+	}
+}
+
+int getb(uint8_t *b, int n) {
+	int p = n >> 3;
+	if (p >= DEPTHB) return 0;
+	int i = b[p] & (1 << (n & 0x7));
+	return i ? 1 : 0;
+}
+
+iptree iptree_new(pos_t size) {
+	iptree t = malloc(size * sizeof(struct node));
+	if (t == 0) error(1, errno, "iptree_new: malloc failed");
+	pos_t i;
+	for(i = 0; i < size; ++i) {
+		t[i].a[0] = i + 1;
+		t[i].a[1] = 0;
+		clearb(t[i].b);
+	}
+	t[i].a[0] = 0;
+	return t;
+}
+
+pos_t iptree_popfree(iptree t) {
+	pos_t f = t[0].a[0];
+	if (f > maxpos) maxpos = f;
+	if (!f) error(1, 0, "iptree_popfree: no free nodes left");
+	t[0].a[0] = t[f].a[0];
+	t[f].a[0] = 0;
+	return f;
+}
+
+void iptree_fold(iptree t, pos_t h, mask_t m) {
+	// check if we can fold
+	for (int i = 0; i < 2; ++i) {
+		pos_t j = t[h].a[i];
+		if (!j || !getb(t[j].b, m - 1)) return;
+	}
+	setb(t[h].b, m, 1);
+}
+
+void iptree_add_new(iptree t, pos_t h, bits b, mask_t m) {
+	if (m) {
+		// there are bits left
+		int l = b[0];  // our bit is left
+		int r = 1 - l; // sibling bit is right
+		// allocate next node element
+		pos_t jl = iptree_popfree(t);
+		// fill current node
+		t[h].a[l] = jl;
+		// recurse to add other bits
+		iptree_add_new(t, jl, b + 1, m - 1);
+		// check if we can fold
+		iptree_fold(t, h, m);
+	} else {
+		// no bits left, this node is terminal
+		setb(t[h].b, 0, 1);
+	}
+}
+
+void iptree_add_rec(iptree t, pos_t h, bits b, mask_t m) {
+	if (m) {
+		// bits to check are left
+		int l = b[0];  // our bit is left
+		pos_t jl = t[h].a[l]; // left subtree head
+		if (jl) {
+			// tree for our bit is not empty, recurse
+			iptree_add_rec(t, jl, b + 1, m - 1);
+		} else {
+			// tree for our bit is missing, fill new subtree
+			iptree_add_new(t, h, b, m);
+		}
+		// check if we can fold
+		iptree_fold(t, h, m);
+	} else {
+		// no bits left, mark this mask
+		setb(t[h].b, 0, 1);
+	}
+}
+
+void iptree_traverse_rec(iptree t, bitsfun f, pos_t h, bits ip, bits mask_b, mask_t m) {
+	if (!h) return;
+
+	int l = MIN(IPMAXLEN + 1 - m, DEPTHL);
+	bit_t b[l];
+	if (l < DEPTHL) {
+		if (l > 0) memcpy(b, mask_b, sizeof(b));
+	} else {
+		memcpy(b, mask_b, sizeof(b) - sizeof(bit_t));
+		b[l - 1] = 0;
+	}
+
+	// find sequences of folded masks folded from lower levels
+	for (int c1 = 0; c1 < l; ++c1) {
+		// skip if mask was processed or is missing in tree
+		if (b[c1] || !getb(t[h].b, c1)) continue;
+		// we found first mask to process
+		b[c1] = 1; // mark it as processed
+		// look for the end of the masks interval
+		int c2 = c1 + 1;
+		for (c2 = c1 + 1; c2 < l; ++c2) {
+			// this time check masks in tree only
+			if (!getb(t[h].b, c2)) break;
+			b[c2] = 1; // mark it as processed
+		}
+		// print prefix with found masks interval
+		f(ip, m, m + c1, m + c2 - 1);
+		// jump to the end of the interval
+		// b[c2] is zero anyway, so ++c1 in "for" will not hurt
+		c1 = c2;
+	}
+
+	// traverse subtrees
+	for (int i = 0; i < 2; ++i) {
+		pos_t j = t[h].a[i];
+		// if subtree exists
+		if (j) {
+			ip[m] = i; // set ip bit
+			// recurse
+			iptree_traverse_rec(t, f, j, ip, b + 1, m + 1);
+		}
+	}
+}
+
+void iptree_traverse(iptree t, pos_t h, bitsfun f) {
+	bit_t ip[IPMAXLEN]; // ip bits
+	bit_t b[DEPTHL]; // processed masks bits
+	bzero(b, sizeof(b));
+	// call recursive traversal
+	iptree_traverse_rec(t, f, h, ip, b, 0);
+}
+
+void print4(bits b, mask_t m, mask_t m1, mask_t m2) {
+	char s_ip[BUFLEN];
+	bits2ip4(b, m, s_ip, BUFLEN);
+	if (m == m1 && m1 == m2) puts(s_ip);
+	else printf("%s{%d,%d}\n", s_ip, m1, m2);
+}
+
+void print6(bits b, mask_t m, mask_t m1, mask_t m2) {
+	char s_ip[BUFLEN];
+	bits2ip6(b, m, s_ip, BUFLEN);
+	if (m == m1 && m1 == m2) puts(s_ip);
+	else printf("%s{%d,%d}\n", s_ip, m1, m2);
+}
+
+double nodes2mb(pos_t n) {
+	return sizeof(struct node) * (double)n / (double)(1 << 20);
+}
+
+int main(void) {
+	bit_t b[IPMAXLEN];
+	mask_t m;
+	char s[BUFLEN];
+
+	iptree t = iptree_new(SIZE);
+	pos_t ip4 = iptree_popfree(t);
+	pos_t ip6 = iptree_popfree(t);
+
+	while (1) {
+		if (!fgets(s, BUFLEN, stdin)) {
+			if (!feof(stdin)) error(1, errno, "input");
+			break;
+		}
+		int l = strlen(s);
+		if (!l) continue;
+		if (s[l - 1] == '\n') s[l - 1] = 0;
+		if (!strchr(s, ':')) {
+			// ipv4
+			ip42bits(s, b, &m);
+			iptree_add_rec(t, ip4, b, m);
+		} else {
+			// ipv6
+			ip62bits(s, b, &m);
+			iptree_add_rec(t, ip6, b, m);
+		}
+	}
+
+	iptree_traverse(t, ip4, print4);
+	iptree_traverse(t, ip6, print6);
+
+	double mb_used = nodes2mb(maxpos);
+	double mb_all = nodes2mb(SIZE);
+	fprintf(stderr, "max nodes: %.2f%%, %d / %d, %.2fMB / %.2fMB\n", maxpos / (double)SIZE * 100.0, maxpos, SIZE, mb_used, mb_all);
+
+	return 0;
+}
diff --git a/plag.c b/plagmax.c
similarity index 100%
rename from plag.c
rename to plagmax.c