UVa 11636 Hello World!

#include<cstdio>
#include<cmath>
using namespace std;

int main()
{
    int n,T=1;
    while(scanf("%d",&n),n>0)
    {
        printf("Case %d: %d\n",T++,(int)ceil(log10(n)/log10(2)));  //换底公式
    }
    return 0;
}