#include <iostream>
#include <cmath>

auto main() -> int {
	long N;
	std::cin >> N;

	long max = 0;
	switch (N) {
		case 0: max = 0;  break;
		case 1: max = 0;  break;
		default:
			long last = std::pow(10, (N-2)/2);
			for (long n = 1; n < last; n *= 10) {
				max += n;
			}
			switch (N%2) {
			case 0: max += 1 * std::pow(10, (N-2)/2); break;
			case 1: max += 7 * std::pow(10, (N-2)/2); break;
			}
	}
	std::cout << max << std::endl;
}