#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  if (fopen("input_muntu.in", "r")) {
    freopen("input_muntu.in", "r", stdin);
    freopen("output_muntu.out", "w", stdout);
  }
  string s;
  cin >> s;
  int n = s.size();
  vector<int> prea(n + 1, 0), preb(n + 1, 0);
  for (int i = 1; i <= n; i++) {
    prea[i] = prea[i - 1];
    preb[i] = preb[i - 1];
    if (s[i - 1] == 'a')
      prea[i]++;
    else if (s[i - 1] == 'b')
      preb[i]++;
  }
  int ans = 0;
  for (int i = 1; i <= n; i++) {
    for (int j = i; j <= n; j++) {
      ans =
          max(ans, prea[i - 1] + preb[j] - preb[i - 1] + prea[n] - prea[j - 1]);
    }
  }
  cout << ans << endl;
  return 0;
}
