diff --git a/atpg b/atpg
index 3bce51b..2978293 100755
Binary files a/atpg and b/atpg differ
diff --git a/circuit.cpp b/circuit.cpp
index 160a4c6..4265924 100644
--- a/circuit.cpp
+++ b/circuit.cpp
@@ -10,7 +10,7 @@ void Circuit::init_stems() {
         if(gate->outputs.size() >= 2) {
             gate->stem = true;
         }
-        //gate->stem = true;
+        // gate->stem = true;
         if(gate->stem) {
             stems.push_back(gate);
         }
@@ -86,6 +86,37 @@ void Circuit::init_topo_index() {
     }
 }
 
+void Circuit::init_gate_level() {
+    MAX_GATE_LEVEL = 0;
+    std::queue<Gate*> q;
+
+    for(Gate* gate : gates) {
+        gate->level = -1;
+    }
+
+    for(auto pi: PIs) {
+        pi->level = 0;
+        q.push(pi);
+    }
+
+    while(!q.empty()) {
+        Gate* g = q.front(); q.pop();
+
+        MAX_GATE_LEVEL = std::max(MAX_GATE_LEVEL, g->level);
+
+        for(Gate* out : g->outputs) {
+            if(out->level == -1) {
+                out->level = g->level + 1;
+                q.push(out);
+            }
+        }
+    }
+
+    for(Gate* g : gates) {
+        assert(g->level != -1);
+    }
+}
+
 void Circuit::print_gates() {
     static const char* type2name[9] = {"AND", "NAND", "OR", "NOR", "XOR", "XNOR", "NOT", "BUF", "IN"};
     for(Gate* gate : gates) {
diff --git a/circuit.h b/circuit.h
index eea1a62..72f505d 100644
--- a/circuit.h
+++ b/circuit.h
@@ -11,6 +11,7 @@ using ll = long long;
 class Gate {
 public:
     int id;
+    int level;
     std::string name;
     enum Type { AND, NAND, OR, NOR, XOR, XNOR, NOT, BUF, INPUT } type;
     int value;
@@ -59,6 +60,10 @@ void print_gates();
 bool is_valid_circuit();
 
 void init_topo_index();
+
+
+int MAX_GATE_LEVEL;
+void init_gate_level();
 void init_stems();
 
 // local search
@@ -81,7 +86,7 @@ int* flip_need_update;
 std::vector<Gate*> flip_update_queue;
 
 // incremental stem struct
-const int STEM_INC = 100;
+const int STEM_INC = 2;
 const int STEM_WEIGHT_MAX = 1e9;
 ll stem_total_weight;
 int stem_total_cnt;
@@ -89,6 +94,7 @@ int* stem_weight;
 int* stem_satisfied;
 
 int fault_propagate_tatal_len;
+int fault_propagate_score;
 
 const int FAULT_INC = 1;
 const int FAULT_WEIGHT_MAX = 20;
diff --git a/ls.cpp b/ls.cpp
index f1f8bec..0cfbe73 100644
--- a/ls.cpp
+++ b/ls.cpp
@@ -217,7 +217,7 @@ ll Circuit::ls_pick_score(Gate* stem) {
 
 ll Circuit::ls_score() {
     //ll score =  - flip_total_weight - stem_total_weight + fault_total_weight + fault_propagate_tatal_len;
-    ll score =  - flip_total_weight - stem_total_weight + fault_propagate_tatal_len;
+    ll score =  - flip_total_weight - stem_total_weight + 10 * fault_propagate_tatal_len;
     return score;
 }
 
@@ -282,6 +282,8 @@ void Circuit::ls_init_data_structs() {
         }
     }
 
+    fault_propagate_score = 0;
+
     fault_propagate_tatal_len = 0;
 
     flip_total_weight = 0;
diff --git a/main.cpp b/main.cpp
index ad17589..e842258 100644
--- a/main.cpp
+++ b/main.cpp
@@ -19,6 +19,7 @@ int main(int args, char* argv[]) {
     circuit->parse_from_file(argv[1]);
     circuit->init_stems();
     circuit->init_topo_index();
+    circuit->init_gate_level();
     printf(" Done.\n");
 
     printf("====== Circuit Statistics ====== \n");
@@ -26,6 +27,7 @@ int main(int args, char* argv[]) {
     printf("PO:\t%ld\n", circuit->POs.size());
     printf("Gate:\t%ld\n", circuit->name2gate.size());
     printf("Stem:\t%ld\n", circuit->stems.size());
+    printf("Level:\t%d\n", circuit->MAX_GATE_LEVEL);
     printf("================================ \n");
 
     std::unordered_set<Fault*> faults;