题解

#include<bits/stdc++.h>
using namespace std;
int main(){
    string a = "4567" ,b = "123" ,c;
    int n;
    cin >> n;
    for (int i = 1 ; i <= n ; i++){  //按照题目执行操作
        c = b + a;
        a = b;
        b = c;
    }
    cout << c[n - 1];  //水题!! :(
    return 0;
}