#3 #5 #10过不去

//代码如下
#include<bits/stdc++.h>
using namespace std;
const int N = 61;
int dp[N][N] , n;
char a[N];
int main(){
	memset(dp , 0x3f3f3f3f , sizeof dp);
	int i = 1;
	while(cin >> a[i]){
		dp[i][i] = 1;
		i ++;
	}
	n = i - 1;
	for(int len = 2;len <= n;len ++){
		for(i = 1;i + len - 1 <= n;i ++){
			int j = i + len - 1;
			if(a[i] != a[j]) dp[i][j] = min(dp[i][j - 1] , dp[i + 1][j]) + 1;
			else dp[i][j] = min(dp[i][j] , dp[i + 1][j]);
		}
	}
	cout << dp[1][n] << endl;
	return 0;
}