UVA 11723 - Numbering Roads

#include <stdio.h>
int main()
{
    int r,n,ncase=0;
    while(scanf("%d%d",&r,&n) && r+n)
    {
        if(r>n*27) printf("Case %d: impossible\n",++ncase);
        else if(r%n) printf("Case %d: %d\n",++ncase,r/n);
        else printf("Case %d: %d\n",++ncase,r/n-1);
    }
    return 0;
}