题解 | #汽水瓶#

#include <iostream>
using namespace std;

int main() {
    int n;
    while(cin >> n){
        int cnt = 0;
        if(n == 0) break;
        while(n){
            int a = n / 3;
            int b = n % 3;
            cnt += a;
            n = a + b;
            if(n == 2){
                cnt ++;
                break;
            }
            if(n == 1) break;
        }
        cout << cnt << endl;
    }
    return 0;
}
// 64 位输出请用 printf("%lld")