foo.cc: In function ‘bool leap(int)’:
foo.cc:6:19: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses]
    6 |         if (x%4==0&&x%100!=0||x%400==0) return true;
      |             ~~~~~~^~~~~~~~~~
foo.cc: In function ‘int yd(int, int, int)’:
foo.cc:20:9: warning: this ‘for’ clause does not guard... [-Wmisleading-indentation]
   20 |         for (int i=1;i<m;i++)
      |         ^~~
foo.cc:22:17: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the ‘for’
   22 |                 return ret;
      |                 ^~~~~~