def repeatedString(s, n):
    # Count 'a's in one full instance of string 's'
    countInOneInstance = s.count('a')

    # Calculate how many full instances of 's' can fit in 'n'
    countInFullInstance = countInOneInstance * (n // len(s))

    # Count 'a's in the remaining part of the string (if any)
    countInPartInstance = 0
    numFirstCharsToCount = n % len(s)

    for i in range(numFirstCharsToCount):
        if s[i] == 'a':
            countInPartInstance += 1

    return countInFullInstance + countInPartInstance

module Main where

solve :: String -> Int -> Int
solve ss n =
    let
        l = length ss
        c = length $ filter (== 'a') ss
        (m, r) = n `divMod` l
        d = length $ filter (== 'a') $ take r ss
     in
        m * c + d

main :: IO ()
main = do
    ss <- getLine :: IO String
    n <- readLn :: IO Int
    print $ solve ss n

long ccount(string s) {
    return count(s.begin(), s.end(), 'a');
}

long repeatedString(string s, long n) {
    return (n / s.size()) * ccount(s) + ccount(s.substr(0, n % s.size()));
}

def repeatedString(s, n):
    a=0
    for i in s:
        if i=="a":
            a+=1
    if n%len(s)==0:
        b=a*(n//len(s))
    else:
        b=a*(n//len(s))
        for i in range(n%len(s)):
            if s[i]=="a":
                b+=1
    return b