#include <bits/stdc++.h>
using namespace std;
template <typename T, typename U>
void amin(T& a, U b) {
  if (a > b) a = b;
}
template <typename T, typename U>
void amax(T& a, U b) {
  if (a < b) a = b;
}
const long long INF = 1e18;
const int32_t M = 1e9 + 7;
void solve() {
  string s;
  cin >> s;
  long long n = s.size();
  vector<long long> cnta(n, 0), cntb(n, 0);
  for (long long i = 0; i < n; i++) {
    if (s[i] == 'a')
      cnta[i] = i > 0 ? cnta[i - 1] + 1 : 1;
    else
      cnta[i] = i > 0 ? cnta[i - 1] : 0;
    if (s[i] == 'b')
      cntb[i] = i > 0 ? cntb[i - 1] + 1 : 1;
    else
      cntb[i] = i > 0 ? cntb[i - 1] : 0;
  }
  long long ans = 0;
  for (long long i = 0; i < n; i++) {
    for (long long j = 0; j < i; j++) {
      if (i >= j) {
        amax(ans, cnta[j] + cnta[n - 1] - cnta[i] + cntb[i] - cntb[j]);
      } else {
        amax(ans, cnta[i] + cnta[n - 1] - cnta[j] + cntb[j] - cntb[i]);
      }
      amax(ans, cntb[j] + cnta[n - 1] - cnta[j]);
    }
  }
  amax(ans, cnta[n - 1]);
  amax(ans, cntb[n - 1]);
  cout << ans << "\n";
}
void input() {}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  input();
  int i = 1;
  { solve(); }
}
