题解 | #走方格的方案数#

n,m = list(map(int,input().split(' '))) #n为横向,m为纵向

#f[i][j] = f[i-1][j] + f[i][j-1] 

dp = [[0 for i in range(m+1)] for j in range(n+1)]

dp[0][0] = 0

for i in range(1,n+1):
    dp[i][0] = 1

for j in range(1,m+1):
    dp[0][j] = 1 

for i in range(1,n+1):
    for j in range(1,m+1):
        dp[i][j] = dp[i-1][j] + dp[i][j-1]

print(dp[n][m])