Grid

n = int(input())
grid = []
for i in range(n):
    row = input()
    grid.append(row)
    
def countColors(grid, n):
    color = 0
    #Columns:
    for column_number in range(n):
        if grid[0][column_number] == '1':
            for row in grid:
                if row[column_number] == '0':
                    if grid[0] != '1'*n:
                        return -1
                    break
            else:
                color += 1

    if color == n:
        return color
    #Rows:
    for row in grid:
        if row == '1'*n:
            color += 1
        else:
            for i in range(n):
                if row[i] == '1':
                    for j in range(n):
                        if grid[j][i] == '0':
                            return -1

    if color == 0:
        for row in grid:
            if row != '0'*n:
                return -1
    return color

print(countColors(grid, n))

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: TIME LIMIT EXCEEDED

Test 20

Verdict: TIME LIMIT EXCEEDED

Test 21

Verdict: TIME LIMIT EXCEEDED

Test 22

Verdict: ACCEPTED