用c语言编程题：输入年月确定该月的天数

main()
{
int year,month,day;
printf("Please enter the year:");
scanf("%d",&year);
printf("Please enter the month:");
scanf("%d",&month);
if(month==1||month==3||month==5||month==7||month==8||month==10||month==12)
day=31;
else
if(month==4||month==6||month==9||month==11)
day=30;
else
if((year%4==0&&year%100!=0)||year%400==0)
day=29;
else day=28;
printf("%d\n",day);
}