diff --git a/drama/Makefile b/drama/Makefile
index 7784df8..d51b680 100644
--- a/drama/Makefile
+++ b/drama/Makefile
@@ -4,7 +4,7 @@ LDIR=lib
 BUILD=obj
 ODIR=src/.obj
 
-CFLAGS=-I$(IDIR) #-ggdb
+CFLAGS=-I$(IDIR) -O3 #-ggdb
 # CXX=g++
 LDFLAGS=
 
diff --git a/drama/src/rev-mc.c b/drama/src/rev-mc.c
index 3efb209..11168ae 100644
--- a/drama/src/rev-mc.c
+++ b/drama/src/rev-mc.c
@@ -394,7 +394,9 @@ rev_mc(size_t sets_cnt, size_t threshold, size_t rounds, size_t m_size, char *o_
 
     if (flags & F_VERBOSE) { print_sets(sets); }
 
-    fn_masks          = find_functions(sets, 6, 30, flags);
+    fprintf(stderr, "Start Find Function\n");
+    fn_masks = find_functions(sets, 6, 30, flags);
+    fprintf(stderr, "Start Find RowMask\n");
     uint64_t row_mask = find_row_mask(sets, fn_masks, mem, threshold, flags);
 
     free_buffer(&mem);
@@ -444,10 +446,12 @@ void
 filter_sets(std::vector<set_t> &sets, size_t set_size)
 {
 
-    for (auto s = sets.begin(); s < sets.end(); s++) {
+    for (auto s = sets.begin(); s < sets.end();) {
         if (s->size() < set_size) {
-            sets.erase(s);
-            s -= 1;
+            s = sets.erase(s);
+            // s -= 1;
+        } else {
+            ++s;
         }
     }
 }