#include<bits/stdc++.h>
#define rep(i,N) for(ll (i)=0;(i)<(N);(i)++)
#define chmax(x,y) x=max(x,y)
#define chmin(x,y) x=min(x,y)
using namespace std;
typedef long long ll;
typedef pair<int,int> P;
const int mod = 1000000007;
const int INF = 1001001001;

int main() {
  string s;
  cin >> s;
  int n = s.length();
  int ans = -1;

  rep(i, n) rep(j, n) {
    string cur = s;
    swap(cur[i], cur[j]);
    int num = stoi(cur);
    if (ans < num) ans = num;
  }

  cout << ans << endl;

}