#define _USE_MATH_DEFINES #include "bits/stdc++.h" using namespace std; #define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i)) #define rep(i,j) FOR(i,0,j) #define each(x,y) for(auto &(x):(y)) #define mp make_pair #define MT make_tuple #define all(x) (x).begin(),(x).end() #define debug(x) cout<<#x<<": "<<(x)<; using vi = vector; using vll = vector; template class ModInt { public: ModInt() :value(0) {} ModInt(long long val) :value((int)(val<0 ? MOD + val % MOD : val % MOD)) { } ModInt& operator+=(ModInt that) { value = value + that.value; if (value >= MOD)value -= MOD; return *this; } ModInt& operator-=(ModInt that) { value -= that.value; if (value<0)value += MOD; return *this; } ModInt& operator*=(ModInt that) { value = (int)((long long)value * that.value % MOD); return *this; } ModInt &operator/=(ModInt that) { return *this *= that.inverse(); } ModInt operator+(ModInt that) const { return ModInt(*this) += that; } ModInt operator-(ModInt that) const { return ModInt(*this) -= that; } ModInt operator*(ModInt that) const { return ModInt(*this) *= that; } ModInt operator/(ModInt that) const { return ModInt(*this) /= that; } ModInt pow(long long k) const { ModInt n = *this, res = 1; while (k) { if (k & 1)res *= n; n *= n; k >>= 1; } return res; } ModInt inverse() const { long long a = value, b = MOD, u = 1, v = 0; while (b) { long long t = a / b; a -= t * b; swap(a, b); u -= t * v; swap(u, v); } return ModInt(u); } int toi() const { return value; } private: int value; }; typedef ModInt<1000000007> mint; ostream& operator<<(ostream& os, const mint& x) { os << x.toi(); return os; } class Combinatons { public: Combinatons(int n = 0) :fact(n + 1), rev(n + 1) { fact[0] = 1; for (int i = 1; i < n + 1; ++i)fact[i] = fact[i - 1] * i; for (int i = 0; i < n + 1; ++i)rev[i] = fact[i].inverse(); } mint C(int n, int r) { if (n < r)return 0; return fact[n] * rev[r] * rev[n - r]; } mint H(int n, int r) { return C(n + r - 1, r); } mint P(int n, int r) { if (r > n)return 0; return fact[n] * rev[n - r]; } mint catalan(int n) { return fact[2 * n] * rev[n + 1] * rev[n]; } private: vector fact, rev; }; void solve() { int N, M; cin >> N >> M; if (N == 1) { cout << 1 << endl; return; } Combinatons cmb(M); mint ans; for (int i = -M, r = 0; i <= M; i += 2, r++) { int j = (i < 0 ? -i - 1 : i) % (2 * N); int x = j < N ? j + 1 : 2 * N - j; if (x == 1) { ans += cmb.C(M, r); } } cout << ans << endl; } int main() { ios::sync_with_stdio(false); cin.tie(0); cout << fixed << setprecision(15); solve(); return 0; }