diff --git a/drama/src/rev-mc.c b/drama/src/rev-mc.c
index 473740f..e3567cc 100644
--- a/drama/src/rev-mc.c
+++ b/drama/src/rev-mc.c
@@ -266,7 +266,8 @@ find_row_mask(std::vector<set_t> &sets,
               std::vector<uint64_t> fn_masks,
               mem_buff_t mem,
               uint64_t threshold,
-              uint64_t flags)
+              uint64_t flags,
+              uint64_t cpu)
 {
 
     addr_tuple base_addr = gen_addr_tuple(get_rnd_addr(mem.buffer, mem.size, 0));
@@ -326,12 +327,13 @@ find_row_mask(std::vector<set_t> &sets,
     // }
 
     std::vector<std::thread> workers;
-    auto thread_num = std::thread::hardware_concurrency();
+    auto thread_num = cpu == 0 ? std::thread::hardware_concurrency() : cpu;
     if (thread_num > 2) { thread_num -= 2; }
     uint64_t step = 0;
     for (uint64_t i = row_mask; i < last_mask; ++step) { i = next_bit_permutation(i); }
     step /= thread_num;
     if (!step) { ++step; }
+    fprintf(stderr, "thread_num: %ld", thread_num);
 
     for (int i = 0; i < thread_num; ++i) {
         workers.emplace_back([&] {
@@ -450,7 +452,7 @@ rev_mc(size_t sets_cnt, size_t threshold, size_t rounds, size_t m_size, char *o_
     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);
+    uint64_t row_mask = find_row_mask(sets, fn_masks, mem, threshold, flags, cpu);
 
     free_buffer(&mem);
 }