C

#include <bits/stdc++.h>

using namespace std;

#define ll     long long
#define pb     push_back
#define ppb    pop_back

int main()
{
    vector<ll int> v;

    string s = "";

    function<void(char)> func = [&](char c)
    {
        s.pb(c);

        v.pb(stoll(s));

        for(char ch=c-1; ch>='0'; ch--)
            func(ch);

        s.ppb();
    };

    for(int ch='0'; ch<='9'; ch++)
        func(ch);

    sort(v.begin(), v.end());

    int k;
    cin>>k;

    cout<<v[k]<<"\n";
}