#include <iostream>

using namespace std;


int main() {
	int n, num[10];
	bool end = false;
	cin >> n;
	int i = 1;
	while (n > 0) {
		num[i] = n % 10;
		n /= 10;
		i++;
	}
	i--;
	num[0] = -1;
	for (int j = i; j > 1; j--) {
		int max = 0;
		for (int k = 1; k < j; k++) {
			if (num[max] < num[k])max = k;
		}
		if (num[j] < num[max]) {
			int t = num[j];
			num[j] = num[max];
			num[max] = t;
			break;
		}
	}
	for (int j = i; j >0; j--) cout << num[j];
	return 0;
}