DIGITS = (
    "73167176531330624919225119674426574742355349194934"
    "96983520312774506326239578318016984801869478851843"
    "85861560789112949495459501737958331952853208805511"
    "12540698747158523863050715693290963295227443043557"
    "66896648950445244523161731856403098711121722383113"
    "62229893423380308135336276614282806444486645238749"
    "30358907296290491560440772390713810515859307960866"
    "70172427121883998797908792274921901699720888093776"
    "65727333001053367881220235421809751254540594752243"
    "52584907711670556013604839586446706324415722155397"
    "53697817977846174064955149290862569321978468622482"
    "83972241375657056057490261407972968652414535100474"
    "82166370484403199890008895243450658541227588666881"
    "16427171479924442928230863465674813919123162824586"
    "17866458359124566529476545682848912883142607690042"
    "24219022671055626321111109370544217506941658960408"
    "07198403850962455444362981230987879927244284909188"
    "84580156166097919133875499200524063689912560717606"
    "05886116467109405077541002256983155200055935729725"
    "71636269561882670428252483600823257530420752963450"
)

def max_adjacent_product(digits, window):
    if window <= 0 or window > len(digits):
        return 0
    best = 0
    for i in range(len(digits) - window + 1):
        prod = 1
        for j in range(window):
            prod *= int(digits[i + j])
        if prod > best:
            best = prod
    return best

def solve(window=13):
    return max_adjacent_product(DIGITS, window)

if __name__ == "__main__":
    assert max_adjacent_product("123456789", 2) == 72, "Checkpoint failed for custom digits"
    assert solve(4) == 5832, "Checkpoint failed for window=4"
    print(solve())