#include <iostream>
#include <algorithm>
#include <cstring>
#include <string>
using namespace std;
const int N = 55;
int f[N][N];
int main()
{
  string s;
  cin >> s;
  int n = s.size();
  memset(f, 0x3f, sizeof f);
  for (int i = 0; i < n; i ++ ) f[i][i] = 1;
  for (int len = 2; len <= n; len ++ )
    for (int i = 0; i + len - 1 < n; i ++ )
    {
      int j = i + len - 1;
      if (s[i] == s[j]) f[i][j] = min(f[i + 1][j], f[i][j - 1]);
      else
        for (int k = i; k < j; k ++ )
          f[i][j] = min(f[i][j], f[i][k] + f[k + 1][j]);
    }
  cout << f[0][n - 1] << endl;
  return 0;
}