PAT1012数字分类测试点问题

程序如下，8个测试点通过7个，最后一个过不了，为什么？？？

 #include <stdio.h>
int main(){
    int i,N,a[1000];
    int flag=1,num_A4=0;
    int count1=0,count2=0,count3=0,count5=0;
    float count4=0;
    scanf("%d",&N);
    for(i=0;i<N;i++)
    {
        scanf("%d",&a[i]);
    if(a[i]%5==0&&a[i]%2==0)
        count1+=a[i];
    if(a[i]%5==1)
        {count2+=flag*a[i];
            flag=-flag;
        }
    if(a[i]%5==2)   
        count3++;
    if(a[i]%5==3)   
        {count4+=a[i];
           num_A4++;
        }
    if(a[i]%5==4){
        if(a[i]>count5)
            count5=a[i];
    }
    }
    if(num_A4!=0)
    count4=1.0*count4/num_A4;
    if(count1)
        printf("%d ",count1);
    else 
        printf("N ");
    if(count2)
        printf("%d ",count2);
    else 
        printf("N ");   
    if(count3)
        printf("%d ",count3);
    else 
        printf("N ");   
    if(count4)
        printf("%.1f ",count4);
    else 
        printf("N ");   
    if(count5)
        printf("%d",count5);    
    else 
        printf("N");
    return 0;
} 

http://blog.csdn.net/xky1306102chenhong/article/details/48090209

你第二个交错求和分类的时候是不是用sum==0判断它存不存在这种数字的，如果交错求和之后的结果为0，它应该返回0