#include <bits/stdc++.h>
using namespace std;
int main() {
  string str;
  cin >> str;
  int len = str.length();
  int cnt[2][len + 5];
  memset(cnt, 0, sizeof(cnt));
  cnt[0][0] = 0;
  cnt[1][0] = 0;
  for (int i = 1; i <= len; i++) {
    cnt[0][i] = cnt[0][i - 1];
    cnt[1][i] = cnt[1][i - 1];
    if (str[i - 1] - 'a' == 0)
      cnt[0][i] += 1;
    else if (str[i - 1] - 'b' == 0)
      cnt[1][i] += 1;
  }
  cnt[0][len + 1] = cnt[0][len];
  cnt[1][len + 1] = cnt[1][len];
  int ans = 0;
  for (int i = 0; i <= len; i++) {
    for (int j = len; j >= i; j--) {
      int cnta, cntb;
      cnta = cnt[0][i] + cnt[0][len] - cnt[0][j];
      cntb = cnt[1][j] - cnt[1][i];
      if (ans < cnta + cntb) ans = cnta + cntb;
    }
  }
  if (ans < cnt[0][len]) ans = cnt[0][len];
  if (ans < cnt[1][len]) ans = cnt[1][len];
  cout << ans;
  return 0;
}
