#include <bits/stdc++.h>

#define el '\n'

typedef long long ll;
typedef long double ld;

#define Beevo ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

using namespace std;

const int N = 100 + 5;

int n;
string s;
int dp[N][N][2];

int solve(int l, int r, bool ch) {
    if (l >= r)
        return 0;

    int &ret = dp[l][r][ch];

    if (~ret)
        return ret;

    ret = solve(l + 2, r - 2, 0) + 2;

    if (ch || s[l] != s[r])
        ret = min(ret, solve(l + 1, r - 1, 1) + 1);

    if (ch && s[l] != s[r] || !ch && s[l] == s[r])
        ret = min(ret, solve(l + 1, r - 1, 0));

    return ret;
}

void testCase() {
    cin >> s;

    n = s.size();

    memset(dp, -1, sizeof dp);

    cout << solve(0, n - 1, 0);
}

signed main() {
    Beevo

    int t = 1;
//    cin >> t;

    while (t--)
        testCase();
}