/in/foo.cc: In function 'int main()':
/in/foo.cc:7:11: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  if(x%4==0&&x%100!=0||x%400==0)
     ~~~~~~^~~~~~~~~~
/in/foo.cc:5:8: warning: unused variable 'r4' [-Wunused-variable]
  int x,r4,r100,r400;
        ^~
/in/foo.cc:5:11: warning: unused variable 'r100' [-Wunused-variable]
  int x,r4,r100,r400;
           ^~~~
/in/foo.cc:5:16: warning: unused variable 'r400' [-Wunused-variable]
  int x,r4,r100,r400;
                ^~~~