/* Problem URL: https://cses.fi/problemset/task/1716 */ #include #include #include using namespace std; using namespace __gnu_pbds; template > using ordered_set = tree; #define V vector #define rmin(a, b) a = min(a, b) #define rmax(a, b) a = max(a, b) #define rep(i, lim) for (int i = 0; i < (lim); i++) #define nrep(i, s, lim) for (int i = s; i < (lim); i++) #define repv(i, v) for (auto &i : (v)) #define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; } #define sortv(v) sort(v.begin(), v.end()) #define all(v) (v).begin(), (v).end() using vi = vector; using vvi = vector; using vvvi = vector; using vvvvi = vector; using ll = long long; using vl = vector; using vvl = vector; using vvvl = vector; using vvvvl = vector; template auto operator<<(ostream &os, const vector &vec)->ostream& { os << vec[0]; for (size_t i = 1; i < vec.size(); i++) { os << ' ' << vec[i]; } os << '\n'; return os; } template auto operator>>(istream &is, vector &vec)->istream& { for (auto &i : vec) { is >> i; } return is; } template auto operator<<(ostream &os, const vector> &vec)->ostream& { for (auto &i : vec) { os << i[0]; for (size_t j = 1; j < i.size(); j++) { os << ' ' << i[j]; } os << '\n'; } return os; } template auto operator>>(istream &is, vector> &vec)->istream& { for (auto &i : vec) { for (auto &j : i) { is >> j; } } return is; } int main() { ios::sync_with_stdio(false); cin.tie(nullptr); int n, m; cin >> n >> m; const ll mod = 1e9 + 7; vl fact(2e6 + 1); fact[0] = 1; nrep(i, 1, fact.size()) { fact[i] = (fact[i - 1] * i) % mod; } auto fpow = [&](ll a, ll b) { ll ans = 1; ll now = a; rep(i, 30) { if ((b >> i) & 1) { ans *= now; ans %= mod; } now *= now; now %= mod; } return ans; }; auto comb = [&](ll n, ll k) { return (fact[n] * fpow((fact[k] * fact[n - k]) % mod, mod - 2)) % mod; }; cout << comb(n + m - 1, m) << '\n'; }