import sys
sys.set_int_max_str_digits(0)
#斯特林数
dp = [[0 for _ in range(105)] for _ in range(105)]
dp[0][0] = 1
for i in range(1,101):
    for j in range(1,i+1):
        dp[i][j] = dp[i-1][j-1]+j*dp[i-1][j]
while True:
    line = input().strip()  # 接收一行输入
    if line == "end":  # 如果输入 'end'，结束循环
        break
    line = line.split()
    print(dp[int(line[0])][int(line[1])])