#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;

int main(){
    string S; cin >> S;
    vi v(sz(S));
    int N = sz(S);
    rep(i, N)v[i] = S[i] - '0';

    int ans = 0;
    vi dp(1 << N, 0);
    rep(mask, 1 << N) {
        rep(k, N)if(!(mask>>k&1))rep(j, k)if(!(mask>>j&1))rep(i, j)if(!(mask>>i&1)) {
            if(v[i] != 0 && v[i] != v[j] && v[j] == v[k]) {
                int val = dp[mask] + v[i] * 100 + v[j] * 10 + v[k];
                smax(ans, val);
                smax(dp[mask | (1 << i) | (1 << j) | (1 << k)], val);
            }
        }
    }
    cout << ans << endl;
}