#include <iostream>
#include <fstream>
using namespace std;

ifstream fin("NUMAR.TXT");

int main() {
    long n, m;
    fin >> n;
    bool cifra = false;
    int x = 1, v[10];
    while (!cifra) {
        int c = n % 10;
        n /= 10;
        if (n == 0) {
            cout << "Nu exista";
            return 0;
        }
        if (c > n % 10) {
            cifra = true;
            m = n / 10 * 10 + c;
            v[x] = n % 10;
            x++;
        }
        else {
            v[x] = c;
            x++;
        }
    }

    x--;
    int vmin = 0;
    while (vmin != 10) {
        vmin = 10;
        for (int i = 1; i <= x; i++)
            if (v[i] < vmin) {
                vmin = v[i];
                v[i] = 10;
            }
        if (vmin != 10)
            m = m * 10 + vmin;
    }
    cout << m;
    return 0;
}