UVa 11636 - Hello World!

最水的題，挺簡單，用數學做的，剛開始判斷負數寫成了-1失誤超時了.

#include <bits/stdc++.h>
using namespace std;

int main()
{
    int n, kase = 0;
    while(cin >> n, n > 0)
        printf("Case %d: %d\n", ++kase, (int)ceil(log2(n)));
    return 0;
}