N = int(input())
A = [input().split() for _ in range(N)]
import sys
if N == 1:
    print(1)
    exit()
    
for h in range(N):
    for w in range(N):
        if A[h][w] == "?":
            x,y = h,w
        else:
            A[h][w] = int(A[h][w])
u = -1
for w in range(N):
    if w == y:continue
    if A[x][w] != 0:
        u = w
        break
num = 0
for h in range(N):
    if h == x:continue
    num += A[h][y] * A[h][u]
ans = -num // A[x][u]
print(ans)