n, m = map(int, input().split())

players = []
for _ in range(m):
    card = []
    for _ in range(n):
        row = list(map(int, input().split()))
        card.append(row)
    lines = []
    # Rows
    for r in range(n):
        lines.append(set(card[r]))
    # Columns
    for c in range(n):
        col = []
        for r in range(n):
            col.append(card[r][c])
        lines.append(set(col))
    # Diagonals
    diag1 = []
    diag2 = []
    for i in range(n):
        diag1.append(card[i][i])
        j = (n - 1) - i
        diag2.append(card[i][j])
    lines.append(set(diag1))
    lines.append(set(diag2))
    players.append(lines)

min_union = float('inf')

for i in range(m):
    for j in range(i + 1, m):
        for line_i in players[i]:
            for line_j in players[j]:
                current_union = len(line_i | line_j)
                if current_union < min_union:
                    min_union = current_union

print(min_union - 1)