2520 10
2520 20
0 0

Case #1: 2520
Case #2: 2600

#include<cstdio>
typedef __int64 LL;
int main()
{
    int cas=1;
    LL i;
    LL x,k;
    while(scanf("%I64d %I64d",&x,&k)!=EOF)
    {
        if(x==0 && k==0)
            break;
        if(k <= 120000)
        {
            for(i = 1; i <= k; i++)
            {
                if(x%i==0)
                    continue;
                else
                    x=(x/i+1)*i;
            }
            printf("Case #%d: ",cas++);
            printf("%I64d\n",x);
        }
        else
        {
            LL y1,y2;
            for(i = 1; i <= 120000; i++)
            {
                if(x%i==0)
                    continue;
                else
                    x=(x/i+1)*i;
            }
            y1=x;
            y2=(x/i+1)*i;
            printf("Case #%d: ",cas++);
            printf("%I64d\n",y1+(k-120000)*(y2-y1));
        }
    }
    return 0;
}