题解 | #走方格的方案数#DP

n, m = list(map(int,input().split()))
dp = [[0 for _ in range(n+1)]for _ in range(m+1)]
#dp[i][j]的含义为从左上角走到坐标为（i，j）的点的走法个数
for i in range(m+1):
    for j in range(n+1):
        if i == 0 or j == 0:
            dp[i][j] = 1
        else:
            dp[i][j] =dp[i-1][j] + dp[i][j-1]  
print(dp[m][n])