#include<iostream>
#include<string>
using namespace std;
int main() {
	int D,x; cin >> D;
	if (D <= 9) {
		cout << D << endl;
	}else {
		x = D / 2 + 5;
		string y = to_string(x);
		if (D % 2 == 0) {
			cout << y[0] << endl;
		}
		else {
			cout << y[1] << endl;
		}
	}
}