/in/foo.cc: In function 'int main()':
/in/foo.cc:6:11: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  if(a%4==0&&a%100!=0||a%400==0) cout<<"YES";
     ~~~~~~^~~~~~~~~~
/in/foo.cc:4:8: warning: unused variable 'b' [-Wunused-variable]
  int a,b,c;
        ^
/in/foo.cc:4:10: warning: unused variable 'c' [-Wunused-variable]
  int a,b,c;
          ^