/*
Given a positive integer n, find the smallest integer which has exactly the same digits existing in the integer n and is greater in value than n. If no such positive integer exists, return -1.

Input format
A 32 bit integer N

Output format
A single integer

Sample Input 1
12

Sample Output 1
21

Explanation
There is only one number greater than 12 which is composed of 2 and 1 and it is 21.

Constraints
0<= N <= 10^9
*/

vector<int> getDigits(int n) {
    vector<int> digits;
    while (n > 0) {
        digits.push_back(n % 10);
        n /= 10;
    }
    reverse(digits.begin(), digits.end());
    return digits;
}

/**
 * @param {number} n
 * @return {number}
 */
// https://www.youtube.com/watch?v=LuLCLgMElus ; TUF
function nextGreaterElementWithSameSetOfDigits(n) {
     let arr=getDigits(n);
     let length=arr.length;
     if(length<=1)
     return -1;
     let index1,index2;
     let i=length-2,j;
     while(i>=0&&arr[i]>=arr[i+1]){
         i--;
     }
     index1=i;
     if(index1>=0){
         i=length-1;
        while(i>=0&&arr[i]<=arr[index1]){
            i--;
        }
        index2=i;
        [arr[index1],arr[index2]]=[arr[index2],arr[index1]];
     }
     else
     return -1;

     // reverse after index1+1;
     i=index1+1;
     j=length-1;
     while(i<j){
         [arr[i],arr[j]]=[arr[j],arr[i]];
         i++;
         j--;
     }
     return parseInt(arr.join(''));


}
/*
function nextGreaterElementWithSameSetOfDigits(n) {
    let arr=getDigits(n);
    // console.log(arr);// order  of digit should be inPlace
    let i,j;
    let length=arr.length;
    let hasFound=false;
    if(n<10)
    return -1;
    for(let i=length-1;i>=0;i--){
        for(let j=i-1;j>=0;j--){
            if(arr[i]>arr[j]){
                [arr[i],arr[j]]=[arr[j],arr[i]];
                hasFound=true;
                break;
            }
        }
        if(hasFound)
            break;
    }
    if(!hasFound)
    return -1;
    return parseInt(arr.join(''));
}
*/

function main() {
    const n = parseInt(readLine(), 10);
    console.log(nextGreaterElementWithSameSetOfDigits(n));
}