#include <bits/stdc++.h>
using namespace std;

int dp[502][502];

int main() {
	string s;
	cin >> s;
	for (int j = 0; j <= (int)s.size(); j++) {
		for (int i = 0; i < (int)s.size() - j; i++) {
			dp[i][i+j] = dp[i+1][i+j] + 1;
			for (int k = i + 1; k <= i + j; k++) {
				if (s[k] == s[i])
					dp[i][i+j] = min(dp[i][i+j], dp[i+1][k-1] + dp[k+1][i+j]);
			}
		}
	}
	cout << dp[0][(int)s.size() - 1] << endl;
}

当输入为 abababa 时，输出 1