foo.cc: In function 'int main()':
foo.cc:11:22: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   if(i%400==0||i%4==0&&i%100!=0)
                ~~~~~~^~~~~~~~~~
foo.cc:8:12: warning: unused variable 'x' [-Wunused-variable]
  int i;int x;
            ^