佬们，帮忙看看为什么80分

#include <stdio.h>
int main()
{
    int s,v,time,h,m;
    scanf("%d%d",&s,&v);
    time = s/v;
    if(s%v!=0)
    {
    time++;
    }
    time+=10;//����
    if(time<=480)
    {
    h = time/60;
    m = time%60;
    printf("0%d:%d",7-h,60-m);
    }
    else
    {
        time = time-480;
        h = (1440-time)/60;
        m = (1440-time)%60;
        if(h<10)
        {
            printf("0");
        }
        printf("%d:",h);
        if(m<10)
        {
            printf("0");
        }
        printf("%d",m);
    }

    return 0;
 }