#define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES
#include <iostream>
#include <map>
#include <list>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <string>
#include <vector>
#include <algorithm>
#include <utility>
#include <queue>
#include <iomanip>

using namespace std;

int main(void)
{
	long long n;
	long long res = 1;
	long long tmp = 1;

	cin >> n;

	

	for (int i = 1; i < n / 2; i++) {
		if(i == (n / 2) - 1 && n % 2 == 1) {
			tmp *= 70;
		} else {
			tmp *= 10;
		}
		res += tmp;
	}

	cout << res << endl;

	return (0);
}