foo.cc: In function ‘bool leap(int)’:
foo.cc:5:18: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses]
    5 |         if(x%4==0&&x%100!=0||x%400==0)return true;
      |            ~~~~~~^~~~~~~~~~
foo.cc: In function ‘int main()’:
foo.cc:18:17: warning: unused variable ‘x’ [-Wunused-variable]
   18 |         int y,m,x;
      |                 ^