/in/foo.cc: In function 'int main()':
/in/foo.cc:27:15: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
    if(x11==11 && y11==10 || x11==10 && y11==11)
       ~~~~~~~~^~~~~~~~~~
/in/foo.cc:59:15: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
    if(x21==21 && y21==20 || x21==20 && y21==21)
       ~~~~~~~~^~~~~~~~~~
/in/foo.cc:7:6: warning: unused variable 'n' [-Wunused-variable]
  int n,i;
      ^