n = int(input())
if n == 1:
    print(1)
else:
    a = []
    i0 = j0 = -1
    for i in range(n):
        row = input().split()
        a.append(row)
        for j in range(n):
            if row[j] == '?':
                i0 = i
                j0 = j

    x = None
    for k in range(n):
        if k == j0:
            continue
        sum_ik = 0
        for i in range(n):
            if i == i0:
                continue
            a_ij = int(a[i][j0])
            a_ik = int(a[i][k])
            sum_ik += a_ij * a_ik
        a_i0k = int(a[i0][k])
        if a_i0k == 0:
            if sum_ik != 0:
                pass  # According to problem statement, input is valid
        else:
            if (-sum_ik) % a_i0k != 0:
                pass  # According to problem statement, input is valid
            x_candidate = (-sum_ik) // a_i0k
            if x is None:
                x = x_candidate
            else:
                if x_candidate != x:
                    pass  # According to problem statement, input is valid
    print(x)