#include <iostream>
#include <cstring>
#include <string>
#include <algorithm>
using namespace std;
string s;
int dp[1010][1010];
//dp[i][j]的含义：从i到j组成的字符串最少要添加几个字符才能恢复成回文串
int DP(int i, int j)
{
    if(i >= j)
        return 0;
    if(dp[i][j] != -1)
        return dp[i][j];
    if(s[i] == s[j])
        dp[i][j] = DP(i+1, j-1);
    else
        dp[i][j] = min(DP(i+1, j), DP(i,j-1))+1;
    return dp[i][j];
}
int main()
{
    memset(dp, -1, sizeof dp);
    cin >> s;
    cout << DP(0, s.size()-1);
    return 0;
}