题解

#include<bits/stdc++.h>
using namespace std;
int main(){
	string a="4567",b="123",c;
	int m,len=0;
	cin>>m;
	while(len<m){
		c=b+a;
		a=b;
		b=c;
		len=c.size();
	}
	cout<<c[m-1];
    return 0;
}