#include <bits/stdc++.h>
using namespace std;
char s[5005];
int num[5005];
int dp[4][5005];
int main() {
  scanf("%s", s);
  int len = strlen(s);
  int tot = 0;
  if (s[0] == 'b') num[tot++] = 0;
  int cnt = 1;
  for (int i = 1; i < len; i++) {
    if (s[i] == s[i - 1])
      cnt++;
    else {
      num[tot++] = cnt;
      cnt = 1;
    }
  }
  num[tot++] = cnt;
  if (s[len - 1] == 'b') num[tot++] = 0;
  memset(dp, 0, sizeof(dp));
  for (int i = 1; i <= 3; i++) {
    for (int j = 1; j <= tot; j++) {
      if (i == 1) {
        if (j % 2)
          dp[i][j] = dp[i][j - 1] + num[j - 1];
        else
          dp[i][j] = dp[i][j - 1];
      } else if (i == 2) {
        if (j % 2)
          dp[i][j] = dp[i][j - 1];
        else
          dp[i][j] = max(dp[i][j - 1], dp[i - 1][j - 1]) + num[j - 1];
      } else {
        if (j % 2)
          dp[i][j] = max(dp[i][j - 1], dp[i - 1][j - 1]) + num[j - 1];
        else
          dp[i][j] = dp[i][j - 1];
      }
    }
  }
  printf("%d\n", dp[3][tot]);
  return 0;
}
