/in/foo.c:22:1: error: unknown type name 'bool'
 bool bfs(int s1,int t)
 ^~~~
/in/foo.c: In function 'main':
/in/foo.c:72:1: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
 while(flow=dfs(S,T,999999999))
 ^~~~~