x, y = map(int, input().split()) # 初始化二维数组 dp = [[0]*y for _ in range(x)] # 将第一列初始化为 1 for i in range(x): dp[i][0] = 1 # 将第一行初始化为 1 for i in range(y): dp[0][i] = 1 # 从第二行第二列开始遍历,每个格子代表到达的路径数 for i in range(1, x): for j in range(1, y): dp[i][j] = dp[i][j-1] + dp[i-1][j] print(dp[x-1][y-1])