diff --git a/graph/mcmf.cc b/graph/mcmf.cc
index 2c28957..543e87c 100644
--- a/graph/mcmf.cc
+++ b/graph/mcmf.cc
@@ -5,7 +5,7 @@ struct mcmf {
         ll flow;
         ll cost;
         int rev;
-        bool mark;
+        int mark;
     };
 
     vector<vector<edge>> edges;
@@ -15,7 +15,7 @@ struct mcmf {
 
     mcmf(int n) : edges(n + 1), dis(n + 1), vis(n + 1) {}
 
-    void add_edge(int from, int to, ll cap, ll cost, bool mark = false) {
+    void add_edge(int from, int to, ll cap, ll cost, int mark = 0) {
         edges[from].push_back({ to, cap, 0, cost, int(edges[to].size()), mark });
         edges[to].push_back({ from, 0, 0, -cost, int(edges[from].size() - 1), mark });
     }