6

4

n = int(input())
count = [0]
def is_safe(queens, row, col):
    for r, c in enumerate(queens):
        if c == col or abs(r - row) == abs(c - col):
            return False
    return True
def solve(queens):
    row = len(queens)
    if row == n:
        count[0] += 1
        return
    for col in range(n):
        if is_safe(queens, row, col):
            solve(queens + [col])
solve([])
print(count[0])