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

template<typename T>
istream& operator >> (istream& istr, vector<T>& v){
    for(T& x: v) istr >> x;
    return istr;
}

template<typename T, typename U>
istream& operator >> (istream& istr, pair<T,U>& p){
    istr >> p.first >> p.second;
    return istr;
}

template<typename T>
ostream& operator << (ostream& ostr, vector<T>& v){
    if(!v.empty()){
        ostr << v.front();
        for(auto itr = ++v.begin(); itr != v.end(); itr++)
            // ostr << *itr;
            ostr << " " << *itr;
    }
    return ostr;
}

template<typename T, typename U>
ostream& operator << (ostream& ostr, pair<T,U>& p){
    // ostr << p.first << p.second;
    ostr << p.first << ", " << p.second;
    return ostr;
}

template<typename T>
ostream& operator << (ostream& ostr, vector<vector<T>>& vv){
    if(!vv.empty()){
        ostr << vv.front();
        for(auto itr = ++vv.begin(); itr != vv.end(); itr++)
            ostr << endl << *itr;
    }
    return ostr;
}

template<typename T, typename U>
ostream& operator << (ostream& ostr, vector<pair<T,U>>& vp){
    if(!vp.empty()){
        ostr << vp.front();
        for(auto itr = ++vp.begin(); itr != vp.end(); itr++)
            ostr << endl << *itr;
    }
    return ostr;
}

typedef long long ll;
typedef vector<ll> vll;
typedef vector<char> vc;
typedef vector<double> vd;
// vll x(n); x[i]=a;
typedef vector<vll> vvll;
typedef vector<vc> vvc;
typedef vector<vd> vvd;
// vvll x(m,vi(n)); x[i][j]=a;
typedef pair<ll,ll> pll;
typedef pair<double,double> pd;
typedef vector<pll> vpll;
typedef vector<pd> vpd;
// vpll x(n); x[i]={a,b}; x[i].first/second;

#define PI 3.1415926535897932
#define EPS 1e-12
#define INF (ll)1e+12
#define REP(i,n) for(ll i=0; i<(n); i++)
#define RREP(i,n) for(ll i=(n)-1; i>=0; i--)
#define FOR(i,a,b) for(ll i=(a); i<(b); i++)
#define FORR(i,a,b) for(ll i=(b)-1; i>=(a); i--)
#define fix(x) cout << fixed << setprecision(x)
#define dump(x) cout << #x << " = " << (x) << endl
#define all(x) (x).begin(),(x).end()

template<typename T> T sum(vector<T>& v){return accumulate(all(v), (T)0);}
template<typename T> inline void sort(vector<T>& v){sort(all(v));}
template<typename T> inline void rsort(vector<T>& v){sort(all(v), greater<T>());}
template<typename T> inline void chmin(T& a, T b){if(a>b) a=b;}
template<typename T> inline void chmax(T& a, T b){if(a<b) a=b;}

ll pow10(ll n){
    ll ans = 1;
    REP(i,n) ans *= 10;
    return ans;
}

int main(){
    ll K;
    cin >> K;

    vvll a(1, vll(0));
    a[0].emplace_back(0);
    FOR(i,1,9+1){
        a.emplace_back(vll(0));
        a[i].emplace_back(i);
        K--;
        if(K==0){
            cout << i << endl;
            return 0;
        }
    }
    FOR(i,1,9+1){
        vvll b(1, vll(0));
        REP(k,a[0].size()) b[0].emplace_back(a[0][k]);
        REP(k,a[1].size()) b[0].emplace_back(a[1][k]);

        FOR(j,1,9+1){
            ll p = pow10(i);
            b.emplace_back(vll(0));
            REP(k, a[j-1].size()){
                b[j].emplace_back(j*p+a[j-1][k]);
                K--;
                if(K==0){
                    cout << b[j][b[j].size()-1] << endl;
                    return 0;
                }
            }
            REP(k, a[j].size()){
                b[j].emplace_back(j*p+a[j][k]);
                K--;
                if(K==0){
                    cout << b[j][b[j].size()-1] << endl;
                    return 0;
                }
            }
            if(j>=9) continue;
            REP(k, a[j+1].size()){
                b[j].emplace_back(j*p+a[j+1][k]);
                K--;
                if(K==0){
                    cout << b[j][b[j].size()-1] << endl;
                    return 0;
                }
            }
        }
        a = b;
    }
    return 0;
}


Measured memory_bytes: 1152