foo.cc: In function ‘int main()’:
foo.cc:8:18: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses]
    8 |         if(x%4==0&&x%100!=0||x%400==0)
      |            ~~~~~~^~~~~~~~~~
foo.cc:8:15: warning: ‘x’ is used uninitialized [-Wuninitialized]
    8 |         if(x%4==0&&x%100!=0||x%400==0)
      |            ~~~^~~
foo.cc:7:13: note: ‘x’ was declared here
    7 |         int x;
      |             ^