foo.cc: In function ‘void isLeap(int)’:
foo.cc:6:29: error: return-statement with a value, in function returning ‘void’ [-fpermissive]
    6 |         if(y%400==0) return 1;
      |                             ^
foo.cc:7:29: error: return-statement with a value, in function returning ‘void’ [-fpermissive]
    7 |         if(y%100==0) return 0;
      |                             ^
foo.cc:8:27: error: return-statement with a value, in function returning ‘void’ [-fpermissive]
    8 |         if(y%4==0) return 1;
      |                           ^
foo.cc:9:16: error: return-statement with a value, in function returning ‘void’ [-fpermissive]
    9 |         return 0;
      |                ^
foo.cc: In function ‘int main()’:
foo.cc:15:18: error: could not convert ‘isLeap(a)’ from ‘void’ to ‘bool’
   15 |         if(isLeap(a)) cout<<"Y";
      |            ~~~~~~^~~
      |                  |
      |                  void