def uniquepaths(m,n): dp=[[1]*n]+[[1]+[0]*(n-1) for _ in range(m-1)] for i in range(1,m): for j in range(1,n): dp[i][j]=dp[i-1][j]+dp[i][j-1] return dp[m-1][n-1] m,n=map(int,input().split()) print(uniquepaths(m,n))