#include <bits/stdc++.h>

using namespace std;

const int N = 1010;

char str[N];
int dp[N][N];
int n;

int main()
{
    cin >> str;
    n = strlen(str);

    for (int len = 1; len <= n; len ++ )
        for (int l = 0; l + len - 1 < n; l ++ )
        {
            int r = l + len - 1;
            if (len == 1) dp[l][r] = 1;
            else
            {
                dp[l][r] = max(dp[l + 1][r], dp[l][r - 1]);
                if (str[l] == str[r]) dp[l][r] = max(dp[l][r], dp[l + 1][r - 1] + 2);
            }
        }

    printf("%d\n", n - dp[0][n - 1]);

    return 0;
}