#include <iostream>
#include <cstring>
using namespace std;
const int XL = 50;
int main()
{
    int n;

    char a [XL];
    char b [XL];
    char c [XL];
    char d [XL];
    char e [XL];
    cin >> a;

    n = strlen(a);

    if (n<=3)
    {
        cout << n;
        return 0;
    }


    if (n%2 == 0)
    {

        for(int j = 0; j < n-1; j++)
        {

            if (a[j+1] != a[n-1-j] )
            {
                cout << n-1-j;
                return 0;
            }

        }




    }

    if (n%2 != 0)
    {
         for(int j = 0; j < n-1; j++)
        {

            if (a[j+1] != a[n-1-j] )
            {
                cout << n-1-j;
                return 0;
            }

        }

    }

    cout << 0;




}