/in/foo.cc: In function 'int main()':
/in/foo.cc:30:25: warning: 'it' may be used uninitialized in this function [-Wmaybe-uninitialized]
    res+=min,s1[edge[it].to]=1;
                ~~~~~~~~~^~
/in/foo.cc:23:12: note: 'it' was declared here
  int res=0,it;
            ^~