Problem: One day Nikita found the string containing letters "a" and "b" only. 

Nikita thinks that string is beautiful if it can be cut into 3 strings (possibly empty) without changing the order of the letters, where the 1-st and the 3-rd one contain only letters "a" and the 2-nd contains only letters "b".

Nikita wants to make the string beautiful by removing some (possibly none) of its characters, but without changing their order. What is the maximum length of the string he can get?

Input

The first line contains a non-empty string of length not greater than 5 000 containing only lowercase English letters "a" and "b". 

Output

Print a single integer — the maximum possible size of beautiful string Nikita can get.

Examples

Input

abba


Output

4

Input

bab


Output

2

Note

It the first sample the string is already beautiful.

In the second sample he needs to delete one of "b" to make it beautiful.

Solution (in PYTHON3):

Solution:
import os
import sys
from io import BytesIO, IOBase
import math
import itertools
import bisect
import heapq
#sys.setrecursionlimit(100000)
#^^^TAKE CARE FOR MEMORY LIMIT^^^
def main():
    pass
BUFSIZE = 8192
class FastIO(IOBase):
    newlines = 0

    def __init__(self, file):
        self._fd = file.fileno()
        self.buffer = BytesIO()
        self.writable = "x" in file.mode or "r" not in file.mode
        self.write = self.buffer.write if self.writable else None

    def read(self):
        while True:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            if not b:
                break
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines = 0
        return self.buffer.read()

    def readline(self):
        while self.newlines == 0:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            self.newlines = b.count(b"\n") + (not b)
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines -= 1
        return self.buffer.readline()

    def flush(self):
        if self.writable:
            os.write(self._fd, self.buffer.getvalue())
            self.buffer.truncate(0), self.buffer.seek(0)


class IOWrapper(IOBase):
    def __init__(self, file):
        self.buffer = FastIO(file)
        self.flush = self.buffer.flush
        self.writable = self.buffer.writable
        self.write = lambda s: self.buffer.write(s.encode("ascii"))
        self.read = lambda: self.buffer.read().decode("ascii")
        self.readline = lambda: self.buffer.readline().decode("ascii")


sys.stdin, sys.stdout = IOWrapper(sys.stdin), IOWrapper(sys.stdout)
input = lambda: sys.stdin.readline().rstrip("\r\n")


def binary(n):
    return (bin(n).replace("0b", ""))


def decimal(s):
    return (int(s, 2))


def pow2(n):
    p = 0
    while (n > 1):
        n //= 2
        p += 1
    return (p)


def primeFactors(n):
    l = []
    while n % 2 == 0:
        l.append(2)
        n = n / 2
    for i in range(3, int(math.sqrt(n)) + 1, 2):
        while n % i == 0:
            l.append(i)
            n = n / i
    if n > 2:
        l.append(int(n))
    return (l)


def isPrime(n):
    if (n == 1):
        return (False)
    else:
        root = int(n ** 0.5)
        root += 1
        for i in range(2, root):
            if (n % i == 0):
                return (False)
        return (True)


def maxPrimeFactors(n):
    maxPrime = -1
    while n % 2 == 0:
        maxPrime = 2
        n >>= 1
    for i in range(3, int(math.sqrt(n)) + 1, 2):
        while n % i == 0:
            maxPrime = i
            n = n / i
    if n > 2:
        maxPrime = n
    return int(maxPrime)


def countcon(s, i):
    c = 0
    ch = s[i]
    for i in range(i, len(s)):
        if (s[i] == ch):
            c += 1
        else:
            break
    return (c)


def lis(arr):
    n = len(arr)
    lis = [1] * n
    for i in range(1, n):
        for j in range(0, i):
            if arr[i] > arr[j] and lis[i] < lis[j] + 1:
                lis[i] = lis[j] + 1
    maximum = 0
    for i in range(n):
        maximum = max(maximum, lis[i])
    return maximum
def isSubSequence(str1, str2):
    m = len(str1)
    n = len(str2)
    j = 0
    i = 0
    while j < m and i < n:
        if str1[j] == str2[i]:
            j = j + 1
        i = i + 1
    return j == m
def maxfac(n):
    root = int(n ** 0.5)
    for i in range(2, root + 1):
        if (n % i == 0):
            return (n // i)
    return (n)
def p2(n):
    c=0
    while(n%2==0):
        n//=2
        c+=1
    return c
def seive(n):
    primes=[True]*(n+1)
    primes[1]=primes[0]=False
    for i in range(2,n+1):
        if(primes[i]):
            for j in range(i+i,n+1,i):
                primes[j]=False
    p=[]
    for i in range(0,n+1):
        if(primes[i]):
            p.append(i)
    return(p)
def ncr(n, r, p):
    num = den = 1
    for i in range(r):
        num = (num * (n - i)) % p
        den = (den * (i + 1)) % p
    return (num * pow(den,
            p - 2, p)) % p
def denofactinverse(n,m):
    fac=1
    for i in range(1,n+1):
        fac=(fac*i)%m
    return (pow(fac,m-2,m))
def numofact(n,m):
    fac=1
    for i in range(1,n+1):
        fac=(fac*i)%m
    return(fac)
def sod(n):
    s=0
    while(n>0):
        s+=n%10
        n//=10
    return s
s=input()
n=len(s)
prea=[0]
preb=[0]
for i in range(0,n):
    if(s[i]=="a"):
        prea.append(prea[-1]+1)
        preb.append(preb[-1])
    else:
        prea.append(prea[-1])
        preb.append(preb[-1]+1)
ans=10**10
for i in range(0,n+1):
    for j in range(i,n+1):
        ac1=prea[i]
        bc1=preb[j]-preb[i]
        ac2=prea[-1]-prea[j]
        #print(ac1,bc1,ac2,i,j)
        ans=min(ans,n-ac1-ac2-bc1)
print(n-ans)