从键盘任意输入一个年号，并判断它是否是润年

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

int main()
{
    int year,flag;
    printf("Enter year:");
    scanf ("%d",&year);
    if(year%4==0&&year%100!=0)
        flag=1;
    else
        flag=0;
    if (year%400==0)
        printf ("%d is a leap year!\n",year);//是闰年
    else
        printf ("%d is not a leap year\n",year);//不是
    return 0;
}