c语言 输入该年月日，求是第几天

#include<stdio.h>
int main()
{
    int riqi(int,int,int);
    int year,month,day,c;
    printf("请输入年月日");
    scanf("%d %d %d",&year,&month,&day);
    c=riqi(year,month,day);
    printf("%d\n",c);
    return 0;
}
int riqi(int year,int month,int day)
{
    int z=0;
    int i;
    int a[12]={31,28,31,30,31,30,31,31,30,31,30,31};
    for(i=1;i<month;i++)
    {
        z=z+a[i];
    }
    if((year%4==0&&year%100!=0||year%400==0)&&month>=3)
        z=z+1;
    return z;
}


结果不对，帮我看看哪里不对啊