foo.cc: In function 'bool rn(int)':
foo.cc:6:22: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
    6 |         return y%4==0&&y%100!=0||y%400==0;
      |                ~~~~~~^~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:30:9: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
   30 |         for(int y=y01;y<y02;y++)
      |         ^~~
foo.cc:32:17: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
   32 |                 ans-=days(y01,m1,d1);
      |                 ^~~

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