#define _USE_MATH_DEFINES #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; typedef long double ld; typedef long long ll; typedef vector vint; typedef vector vll; typedef pair pii; typedef pair pll; typedef pair pdd; typedef complex compd; #define quickIO() {cin.tie(0); cout.sync_with_stdio(false);} #define reach(i,a) for(auto i:a) #define rep(i,n) for(int i=0;i<((int)n);i++) #define REP(i,n) for(int i=0;i<=((int)n);i++) #define srep(i,a,n) for(int i=a;i<((int)n);i++) #define SREP(i,a,n) for(int i=a;i<=((int)n);i++) #define rrep(i,n) for(int i=n-1;i>=0;i--) #define RREP(i,n) for(int i=n;i>=0;i--) #define all(a) (a).begin(),(a).end() #define mp(a,b) make_pair(a,b) #define mt make_tuple #define pb push_back template istream & operator >> (istream & is, vector & vec) { for (T& x : vec) is >> x; return is; } template ostream& operator << (ostream & os, vector & vec) { os << "["; rep(i, vec.size()) os << (i ? ", " : "") << vec[i]; os << "]"; return os; } template istream & operator >> (istream & is, pair & p) { is >> p.first >> p.second; return is; } template ostream& operator << (ostream & os, pair & p) { os << p.first << " " << p.second; return os; } int bitcnt(ll x) { x = ((x & 0xAAAAAAAAAAAAAAAA) >> 1) + (x & 0x5555555555555555); x = ((x & 0xCCCCCCCCCCCCCCCC) >> 2) + (x & 0x3333333333333333); x = ((x & 0xF0F0F0F0F0F0F0F0) >> 4) + (x & 0x0F0F0F0F0F0F0F0F); x = ((x & 0xFF00FF00FF00FF00) >> 8) + (x & 0x00FF00FF00FF00FF); x = ((x & 0xFFFF0000FFFF0000) >> 16) + (x & 0x0000FFFF0000FFFF); x = ((x & 0xFFFFFFFF00000000) >> 32) + (x & 0x00000000FFFFFFFF); return x; } int bitcnt(int x) { x = ((x & 0xAAAAAAAA) >> 1) + (x & 0x55555555); x = ((x & 0xCCCCCCCC) >> 2) + (x & 0x33333333); x = ((x & 0xF0F0F0F0) >> 4) + (x & 0x0F0F0F0F); x = ((x & 0xFF00FF00) >> 8) + (x & 0x00FF00FF); x = ((x & 0xFFFF0000) >> 16) + (x & 0x0000FFFF); return x; } ll sqrtll(ll x) { ll left = 0, right = x; rep(i, 100) { ll mid = (left + right) >> 1; if (mid * mid <= x) left = mid; else right = mid; } return left; } ll gcd(ll a, ll b) { return b == 0 ? a : gcd(b, a % b); } #define debug(x) printf("Case #%d: ", x) #define DEBUG 0 const ld infl = 1e100; const ll mod = 1e9 + 7; const ld eps = 1e-9; const ll inf = 1e18; const int dx[] = { 1,0,-1,0,0 }; const int dy[] = { 0,1,0,-1,0 }; ll frac[2000010], inv_frac[2000010]; ll powmod(ll a, ll b) { ll ret = 1; while (b > 0) { if (b & 1) ret = (ret * a) % mod; a = (a * a) % mod; b >>= 1; } return ret; } ll nCm(ll n, ll m) { return frac[n] * (inv_frac[m] * inv_frac[n - m] % mod) % mod; } int main() { ll n, m; cin >> n >> m; if (n == 1) { cout << 1 << endl; return 0; } frac[0] = frac[1] = inv_frac[0] = inv_frac[1] = 1; SREP(i, 2, m) { frac[i] = frac[i - 1] * i % mod; inv_frac[i] = inv_frac[i - 1] * powmod(i, mod - 2) % mod; } ll pos = -m; ll ret = 0; while (pos <= m) { // (-2n, -2n+1), (0, 1), (2n, 2n+1), ... int pos_mod = ((pos % (2 * n)) + 2 * n) % (2 * n); if (pos_mod == 0 || pos_mod == 1) { // k = m - posとして、mCpos * kC(k/2) int abs_pos = abs(pos); int k = m - abs_pos; if (k % 2 == 0) { (ret += nCm(m, abs_pos + k / 2)) %= mod; } } pos++; } cout << ret << endl; return 0; }