foo.c: In function 'main':
foo.c:6:13: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
    6 |  if((a%4==0)&&(a%100!=0)||(a%400==0))
      |     ~~~~~~~~^~~~~~~~~~~~
foo.c:4:16: warning: unused variable 's' [-Wunused-variable]
    4 |  int a,b,c,k=0,s,i;
      |                ^
foo.c:5:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    5 |  scanf("%d %d %d",&a,&b,&c);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~

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