#include <stdio.h>
#include <time.h>
#define SIZE 100000

int main(void)
{


    char s[SIZE] = {0};
    gets(s);

    clock_t start = clock();
    char subs[SIZE] = "-1\0";
    int cb = 0, ce = 0;
    int ab = 0, ae = 0;

    for (int i = 0; /*i < SIZE && */ s[i]; ++i){
        cb = i;
        ce = i;
        for (int j = i+1; /*j < SIZE* &&*/ s[j]; ++j)
        {
            if (s[i] == s[j]){
                for (int k = ((j-i)/2)-1;  k > 0 /*(j-i)/2*/; k /= 2){
                    if ( s[i+k] != s[j-k]){
                        ce = j;
                    }
                }
            }
            else{
                ce = j;
            }
        }
        long al  = ae - ab, cl = ce - cb;
        if ( al < cl)
        {
            ae = ce;
            ab = cb;
            continue;
        }
        if (al == cl )
        {
            int i1 = ab,  i2 = cb;
            for (; i1 <= ae, i2 <= ce; ++i1, ++i2){
                if (s[i1] < s[i2])
                    goto notless;
                if (s[i1] > s[i2])
                    break;
            }

            ae = ce;
            ab = cb;
            notless:
            continue;
        }
    }
    if ((ae-ab) > 0){
        for (int i = ab ; i <= ae; ++i)
            subs[i-ab] = s[i];
        subs[ae-ab+1] = 0;
    }
    double t = (double)((clock() - start) / CLOCKS_PER_SEC) ;
    printf("%s\n%lf",subs, t);
    fflush(stdin);
    getc(stdin);
    return 0;
}