diff --git a/graph/edmonds-karp.cc b/graph/edmonds-karp.cc
index f789040..1bb27c0 100644
--- a/graph/edmonds-karp.cc
+++ b/graph/edmonds-karp.cc
@@ -11,7 +11,7 @@ struct edmonds_karp {
 
     edmonds_karp(int n) : edges(n + 1) {}
 
-    void add_edge(int from, int to, ll cap, int mark = false) {
+    void add_edge(int from, int to, ll cap, int mark = 0) {
         edges[from].push_back({to, cap, 0, make_pair(to, int(edges[to].size())), mark});
         edges[to].push_back({from, 0, 0, make_pair(from, int(edges[from].size() - 1)), mark});
     }