N = int(input())
M = int(input())

if M > N:
    print(0)
else:
    # Initialize Stirling numbers table
    stirling = [[0] * (M + 1) for _ in range(N + 1)]
    stirling[0][0] = 1
    for i in range(1, N + 1):
        for k in range(1, min(M, i) + 1):
            stirling[i][k] = stirling[i-1][k-1] + k * stirling[i-1][k]
    
    # Calculate M!
    factorial = 1
    for i in range(1, M + 1):
        factorial *= i
    
    print(stirling[N][M] * factorial)