练习3-5 输出闰年

#include
int main(){
    int year;
    scanf("%d",&year);
    if(year<2000||year>2100){
    	printf("Invalid year!");
	}else if(year<2004){
	 		printf("None");
	}else{
        for(int i=2004;i<=year;i+=4){
        if((i%4==0&&i%100!=0)||i%400==0){
     	printf("%d",i);
     	if(i