#include <vector>
#include <string> 
#include <set> 
#include <map> 
#include <unordered_set>
#include <unordered_map>
#include <queue> 
#include <bitset> 
#include <stack>
#include <list>

#include <numeric> 
#include <algorithm> 
#include <random>
#include <chrono>

#include <cstdio>
#include <fstream>
#include <iostream> 
#include <sstream> 
#include <iomanip>
#include <climits>

#include <cctype>
#include <cmath> 
#include <ctime>
#include <cassert>

using namespace std;

#define ULL unsigned long long
#define LL long long
#define PII pair <int, int>
#define VB vector <bool>
#define VI vector <int>
#define VLL vector <LL>
#define VD vector <double>
#define VS vector <string>
#define VPII vector <pair <int, int> >
#define VVI vector < VI >
#define VVB vector < VB >
#define SI set < int >
#define USI unordered_set <int>
#define MII map <int, int>
#define UMII unordered_map <int, int>
#define MS multiset
#define US unordered_set
#define UM unordered_map
#define UMS unordered_multiset
#define UMM unordered_multimap

#define FORN(i, n) for(int i = 0; i < (n); ++i)
#define FOR(i, a, b) for(int i = (a); i <= (b); ++i)
#define FORD(i, a, b) for(int i = (a); i >= (b); --i)

#define SZ size()
#define BG begin() 
#define EN end() 
#define CL clear()
#define X first
#define Y second
#define RS resize
#define PB push_back
#define MP make_pair
#define ALL(x) x.begin(), x.end()
#define INS insert
#define ER erase
#define CNT count

const int MOD = 1e9 + 7;
const int MAX = 1e5;

int b, c;
VI inv(MAX + 1);

int main()
{
	inv[1] = 1;
	FOR(i, 2, MAX) inv[i] = (LL)(MOD - MOD / i) * inv[MOD % i] % MOD;

	cin >> b >> c;

	int x = c - b - 1, k = b; //x * "a", y * "b", cnt[a] - cnt[b] < k
	LL all = 1, bad = 0, sol = 0;
	FOR(y, 0, x + k - 1)
	{
		sol = (sol + all) % MOD;
		sol = (sol - bad) % MOD;
		if (sol < 0) sol += MOD;
		all = all * (x + y + 1) % MOD;
		all = all * inv[y + 1] % MOD; //C_{x + y}^y
		if (y == k - 1) bad = 1;
		else 
			if (y >= k) 
			{
				bad = bad * (x + y + 1) % MOD;
				bad = bad * inv[y - k + 1] % MOD; //C_{x + y}^{y - k}
			}
	}
	cout << sol;

	return 0;
}