题解 | #汽水瓶#

#include <bits/stdc++.h>
using namespace std;
int ans = 0;

void dfs(int n){
    if(n==3||n==2){
        ans++;
        return;
    }
      
    if(n==1)
        return ;
    int quo = 0,rem = 0;
    quo = n / 3;
    rem = n % 3;
    ans += quo;
    dfs(quo+rem);
}

int main() {
    int n;
    while(cin>>n){
        ans = 0;
        if(n == 0)
            break;
        dfs(n);
        cout<<ans<<endl;
    }
    return 0;
}