from functools import reduce

count = 0
time = 0
my_bus = 0
ids = []

#https://rosettacode.org/wiki/Chinese_remainder_theorem

def chinese_remainder(n, a):
    sum = 0
    prod = reduce(lambda a, b: a*b, n)
    for n_i, a_i in zip(n, a):
        p = prod // n_i
        sum += a_i * mul_inv(p, n_i) * p
    return sum % prod

def mul_inv(a, b):
    b0 = b
    x0, x1 = 0, 1
    if b == 1: return 1
    while a > 1:
        q = a // b
        a, b = b, a%b
        x0, x1 = x1 - q * x0, x0
    if x1 < 0: x1 += b0
    return x1

with open("door13_input.txt","r") as f:
    earliest = int(f.readline())
    busses = f.readline().split(",")
    for id in busses:
        if id != "x":
            ids.append((count,int(id)))
        count += 1

n = []
a = []


for index,id in ids:
    n.append(id)
    a.append(id-index)

print(chinese_remainder(n,a))