N, M = gets.split(" ").map{|s| s.to_i}

MOD = 1000000007

nCr = 1
sum = nCr
inv = [0, 1]

j = 1
(N+1).upto(M) {|i|
	nCr = ((nCr * i % MOD) * inv[j]) % MOD
	sum = (sum + nCr) % MOD
	j += 1
	inv[j] = MOD - inv[MOD % j] * (MOD / j) % MOD
}

puts sum