#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll=long long;
using ld=long double;
ld pie=3.141592653589793;
ll inf=1444440099999944;
ll mod=1000000007;
int main(){
    ll n;
    cin >> n;
    n-=1;
    ll x=0;
    vector<ll>a;
    for (ll i = 1; i <10; i++)
    {
        for (ll j = i+1; j < 10; j++)
        {
            x+=1;
            a.push_back(i*10+j);
        }
    }
    sort(a.begin(),a.end());
    ll y=a[n%x];
    ll z=n/x;
    string s=to_string(y);
    for (ll i = 0; i < z; i++)
    {
        s.push_back(s[s.size()-1]);
    }
    cout << s << endl;
}