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

int main()
{
	int N;
	cin >> N;
	vector<int> v;
	for( int i = 1; i < 10; i++ ) {
		for( int j = i + 1; j < 10; j++ ) v.push_back( i * 10 + j );
	}
	int sz = v.size();
	int d = (N - 1) / sz;
	int m = (N - 1) % sz;
	string ans = to_string( v[m] );
	char c = ans.back();
	for( int i = 0; i < d; i++ ) ans += c;

	cout << ans << endl;
}