Two Bags of Potatoes

#include<stdio.h>
int main()
{
    int y,n,k,i,j,m,y1,k1;
    scanf("%d %d %d",&y,&k,&n);
    y1=(y/k+1)*k;
    if(y1<=n)
    {
        while(y1<=n)
        {
            while(y1-y<=0)y1+=k;
            printf("%d ",y1-y);
            y1+=k;    
        }
    }
    else printf("-1");
    return 0;
}

http://codeforces.com/contest/239/problem/A

很悲剧的说 不论是多么简单的题目。。我都要错上多次才能AC。