#include <bits/stdc++.h>

const int maxn = 55;
char s[maxn];
int f[maxn][maxn];

int main() {
	freopen("tuse.in","r",stdin);
	freopen("tuse.out","w",stdout);
	scanf("%s",s + 1);
	int n = strlen(s + 1);
	memset(f , 0x3f , sizeof(f));
	for(int i = 1;i <= n;++ i)
		f[i][i] = 1;
	for(int len = 2;len <= n;++ len) {
		for(int i = 1;i + len - 1 <= n;++ i) {
			int j = i + len - 1;
			if(s[i] == s[j])f[i][j] = std::min(f[i + 1][j] , f[i][j - 1]);
			else {
				for(int k = i;k < j;++ k)
					f[i][j] = std::min(f[i][j] , f[i][k] + f[k + 1][j]);
			}
		}
	}
	printf("%d\n",f[1][n]);
	return 0;
}