foo.c: In function 'main':
foo.c:6:13: warning: unused variable 'sum2' [-Wunused-variable]
  int sum1=0,sum2=0;
             ^~~~
foo.c:6:6: warning: unused variable 'sum1' [-Wunused-variable]
  int sum1=0,sum2=0;
      ^~~~
foo.c: In function 'day':
foo.c:31:14: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
     if(i%4==0&&i%100!=0||i%400==0)//闰年
        ~~~~~~^~~~~~~~~~
foo.c: In function 'main':
foo.c:7:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&a);
  ^~~~~~~~~~~~~~
foo.c:8:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&b);
  ^~~~~~~~~~~~~~
foo.c:9:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&c);
  ^~~~~~~~~~~~~~
foo.c:10:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&d);
  ^~~~~~~~~~~~~~
foo.c:11:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&e);
  ^~~~~~~~~~~~~~
foo.c:12:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&f);
  ^~~~~~~~~~~~~~
foo.c: In function 'day':
foo.c:30:6: warning: 'sum1' may be used uninitialized in this function [-Wmaybe-uninitialized]
  int sum1;
      ^~~~

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