#include <iostream>
#include <string>

using namespace std;

const int N = 1010;

int n;
char s[N];
int f[N][N];

int main() {
    string s;
    cin >> s;
    int n = s.size();

    for (int len = 1; len <= n; ++len) {
        for (int i = 0; i + len - 1 < n; ++i) {
            int j = i + len - 1;
            if (len == 1) {
                f[i][j] = 1;
            } else {
                f[i][j] = max(f[i + 1][j], f[i][j - 1]);
                if (s[i] == s[j]) {
                    f[i][j] = max(f[i][j], f[i + 1][j - 1] + 2);
                }
            }
        }
    }
    cout << n - f[0][n - 1] << endl;
    return 0;
}