C语言：实现一个函数判断year是不是闰年

#include<stdio.h>
#include<stdlib.h>

int leap(int year)
{
int ret = 0;;
if (((year % 4 == 0)
&& (year % 100 != 0))
|| (year % 400 == 0))
{
return 1;
}
else
{
return -1;
}
}

int main()
{
int Year = 0;
printf("please input the year:\n");
scanf("%d", &Year);
int ret = leap(Year);   /*将调用得到的函数值返回到ret中*/
if (ret == 1)
{
printf("%d is leap year!", Year);
}
else
{
printf("%d is not leap year!", Year);
}
system("pause");
return 0;
}