输入2020为什么输出却是20(语言-c语言)

#include
int main()
{
int a;
scanf("%d",&a);
if((a%400==0)||(a%4==0)&&(a%100!=0))
printf("%d is a leap year with an even numbers.");
else
printf("No");
}
为什么在输入2020后的结果是20 is a leap year with an even numbers.

第七行改为：
printf("%d is a leap year with an even numbers.",a);

printf("%d is a leap year....", a);
后面的参数a不能漏掉

if(a%400==0 || (a%4==0&& a%100!=0))
printf("%d is a leap year with an even numbers.",a);缺个变量a

• 可以看下c语言参考手册中的 c语言-exp()