/in/foo.cc: In function 'int main()':
/in/foo.cc:50:6: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
    if(mp[i][j]==0)
      ^
/in/foo.cc:47:6: warning: unused variable 'ff' [-Wunused-variable]
  int ff=1;
      ^~