# PROJECT EULER PROBLEM 8 - Largest Product in a Series

number = ''
number += '73167176531330624919225119674426574742355349194934'
number += '96983520312774506326239578318016984801869478851843'
number += '85861560789112949495459501737958331952853208805511'
number += '12540698747158523863050715693290963295227443043557'
number += '66896648950445244523161731856403098711121722383113'
number += '62229893423380308135336276614282806444486645238749'
number += '30358907296290491560440772390713810515859307960866'
number += '70172427121883998797908792274921901699720888093776'
number += '65727333001053367881220235421809751254540594752243'
number += '52584907711670556013604839586446706324415722155397'
number += '53697817977846174064955149290862569321978468622482'
number += '83972241375657056057490261407972968652414535100474'
number += '82166370484403199890008895243450658541227588666881'
number += '16427171479924442928230863465674813919123162824586'
number += '17866458359124566529476545682848912883142607690042'
number += '24219022671055626321111109370544217506941658960408'
number += '07198403850962455444362981230987879927244284909188'
number += '84580156166097919133875499200524063689912560717606'
number += '05886116467109405077541002256983155200055935729725'
number += '71636269561882670428252483600823257530420752963450'
number_len = len(number)

digit_span = 13

largest = 1
largest_i = 12
for i in range(digit_span):
    largest *= int(number[i])
product = largest
for i in range(digit_span,number_len):
    #product = 1
    old_number = int(number[i-digit_span])
    new_number = int(number[i])
    if old_number == 0:
        product = 1
        for j in range(i+1-digit_span,i+1):
            product *= int(number[j])
    else:
        product = product//old_number*new_number
    print(product)
    if product > largest:
        largest = product
        largest_i = i

print(largest)


