#include <bits/stdc++.h>
using namespace std;
int getDelCountaba(string &s, int bpos) {
  int result = 0;
  int i = bpos;
  for (; i >= 0; i--) {
    if (s[i] != 'b') break;
  }
  for (; i >= 0; i--) {
    if (s[i] != 'a') result++;
  }
  i = bpos;
  for (; i < s.size(); i++) {
    if (s[i] != 'b') break;
  }
  for (; i < s.size(); i++) {
    if (s[i] != 'a') result++;
  }
  return result;
}
int getDelCountab(string &s, int bpos) {
  int result = 0;
  int i = bpos;
  for (; i >= 0; i--) {
    if (s[i] != 'b') break;
  }
  for (; i >= 0; i--) {
    if (s[i] != 'a') result++;
  }
  i = bpos;
  for (; i < s.size(); i++) {
    if (s[i] != 'b') result++;
  }
  return result;
}
int getDelCountba(string &s, int bpos) {
  int result = 0;
  int i = bpos;
  for (; i >= 0; i--) {
    if (s[i] != 'b') result++;
  }
  i = bpos;
  for (; i < s.size(); i++) {
    if (s[i] != 'b') break;
  }
  for (; i < s.size(); i++) {
    if (s[i] != 'a') result++;
  }
  return result;
}
int getDelCountb(string &s) {
  int result = 0;
  for (int i = 0; i < s.size(); i++) {
    if (s[i] != 'b') result++;
  }
  return result;
}
int getDelCounta(string &s) {
  int result = 0;
  for (int i = 0; i < s.size(); i++) {
    if (s[i] != 'a') result++;
  }
  return result;
}
int getCharCount(vector<int> &arr, int left, int right) {
  if (right < left) return 0;
  return arr[right + 1] - arr[left];
}
void solve() {
  string s;
  cin >> s;
  vector<int> lefta;
  vector<int> leftb;
  lefta.resize(s.size() + 1);
  leftb.resize(s.size() + 1);
  for (int i = 1; i < lefta.size(); i++) {
    lefta[i] = lefta[i - 1];
    leftb[i] = leftb[i - 1];
    if (s[i - 1] == 'a')
      lefta[i]++;
    else
      leftb[i]++;
  }
  int maxlen = -1;
  for (int i = 0; i < s.size(); i++) {
    for (int blen = 0; blen <= s.size() - i; blen++) {
      int leftdel = i >= 1 ? getCharCount(leftb, 0, i - 1) : 0;
      int rightdel =
          blen < s.size() ? getCharCount(leftb, i + blen, s.size() - 1) : 0;
      int adelinb = blen > 0 ? getCharCount(lefta, i, i + blen - 1) : 0;
      int cr = s.size() - (leftdel + rightdel + adelinb);
      if (cr > maxlen) maxlen = cr;
    }
  }
  cout << maxlen << endl;
}
int main() {
  std::ios::sync_with_stdio(false);
  cin.tie(0);
  solve();
  return 0;
}
