#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int nextPermutation(char* arr, int len) {
    // Find the largest index i such that arr[i] < arr[i + 1]
    int i = len - 2;
    while (i >= 0 && arr[i] >= arr[i + 1]) {
        i--;
    }
    
    if (i == -1) {
        return 0; // No next permutation
    }
    
    // Find the largest index j such that arr[i] < arr[j]
    int j = len - 1;
    while (arr[j] <= arr[i]) {
        j--;
    }
    
    // Swap arr[i] and arr[j]
    char temp = arr[i];
    arr[i] = arr[j];
    arr[j] = temp;
    
    // Reverse the suffix starting at arr[i + 1]
    int left = i + 1;
    int right = len - 1;
    while (left < right) {
        temp = arr[left];
        arr[left] = arr[right];
        arr[right] = temp;
        left++;
        right--;
    }
    
    return 1;
}

void reverseString(char* str) {
    int len = strlen(str);
    for (int i = 0; i < len / 2; i++) {
        char temp = str[i];
        str[i] = str[len - 1 - i];
        str[len - 1 - i] = temp;
    }
}

static char result[200];

char* solution(char* num) {
    int n = strlen(num);
    
    if (n == 1) {
        strcpy(result, "");
        return result;
    }
    
    // For palindrome, take first half including middle for odd length
    int halfLen = (n + 1) / 2;
    char leftHalf[100];
    strncpy(leftHalf, num, halfLen);
    leftHalf[halfLen] = '\0';
    
    // Find next permutation of left half
    if (!nextPermutation(leftHalf, halfLen)) {
        strcpy(result, "");
        return result;
    }
    
    // Create palindrome by mirroring
    if (n % 2 == 0) {
        // Even length
        strcpy(result, leftHalf);
        char reversed[100];
        strcpy(reversed, leftHalf);
        reverseString(reversed);
        strcat(result, reversed);
    } else {
        // Odd length - exclude middle when mirroring
        strcpy(result, leftHalf);
        char mirrorPart[100];
        strncpy(mirrorPart, leftHalf, halfLen - 1);
        mirrorPart[halfLen - 1] = '\0';
        reverseString(mirrorPart);
        strcat(result, mirrorPart);
    }
    
    return result;
}

int main() {
    char num[100];
    fgets(num, sizeof(num), stdin);
    num[strcspn(num, "\n")] = 0;
    printf("%s\n", solution(num));
    return 0;
}