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

int isPalindrome(char* s, int start, int end) {
    while (start < end) {
        if (s[start] != s[end]) return 0;
        start++;
        end--;
    }
    return 1;
}

char* solution(char* s) {
    int n = strlen(s);
    if (n == 0) {
        char* result = malloc(1);
        result[0] = '\0';
        return result;
    }
    
    int maxLen = 1, start = 0;
    
    for (int i = 0; i < n; i++) {
        for (int j = i; j < n; j++) {
            if (isPalindrome(s, i, j)) {
                if (j - i + 1 > maxLen) {
                    maxLen = j - i + 1;
                    start = i;
                }
            }
        }
    }
    
    char* result = malloc(maxLen + 1);
    strncpy(result, s + start, maxLen);
    result[maxLen] = '\0';
    return result;
}

int main() {
    char line[1000];
    fgets(line, sizeof(line), stdin);
    
    // Remove quotes and newline
    char* s = line;
    if (s[0] == '"') s++;
    int len = strlen(s);
    if (len > 0 && s[len-1] == '\n') s[len-1] = '\0';
    if (len > 1 && s[len-2] == '"') s[len-2] = '\0';
    
    char* result = solution(s);
    printf("\"%s\"\n", result);
    free(result);
    return 0;
}