C++ :

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

int main(){
	int n;
	cin>>n;
	string s1,s2,s3 = "";
	s1 = "4567";
	s2 = "123";
	while(s3.size() < n){
		s3 = s2 + s1;
		s1 = s2;
		s2 = s3;
	}
	
	cout<<s3[n - 1]<<endl;
}