#include <map>
#include <set>
#include <list>
#include <cmath>
#include <deque>
#include <stack>
#include <queue>
#include <bitset>
#include <cstdio>
#include <string>
#include <vector>
#include <random>
#include <chrono>
#include <utility>
#include <numeric>
#include <cstdlib>
#include <cstring>
#include <climits>
#include <sstream>
#include <assert.h>
#include <iostream>
#include <iomanip>
#include <algorithm>
#include <functional>
#include <unordered_map>
using namespace std;

void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(bool x) {cerr << (x ? "true" : "false");}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}

template<typename T, typename V> void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i : x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";} void _print() {cerr << "]\n";}
template <typename T, typename... V>void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifdef HOME
#warning CHECK int:ll::INT_MAX:LLONG_MAX
#define maxn 20
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define maxn 2000006
#define gcd __gcd
#define debug(x...)
#endif

#define ff first
#define endl '\n'
#define ss second
#define inf 0x3f3f3f3f
#define MOD 1000000007
#define PI 3.14159265358979323846264338327950L
#define f(i,x,n) for(int i=x;i<=n;i++)
#define fr(i,x,n) for(int i=x;i>=n;i--)
struct _ { ios_base::Init i; _() { ios_base::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL); } } _;

int dx[] = { -1, 0, 1, 0, -1, -1, 1, 1};
int dy[] = {0, 1, 0, -1, -1, 1, 1, -1};


int main() {

	int n, l; cin >> n >> l;
	int t = (n * (2 * l + (n - 1))) / 2;
	debug(t);
	int i = min(n, max(1, 1 - l));
	int q1 = (l + max(1, (i - 1)) - 1);
	int q2 = (l + i - 1);
	int q3 = (l + min(n, (i + 1)) - 1);

	debug(i, q2, q2, q3);

	int min_diff = min({abs(q1), abs(q2), abs(q3)});

	if (abs(q1) == min_diff) cout << t - q1;
	else if (abs(q2) == min_diff) cout << t - q2;
	else cout << t - q3;
	return 0;
}
#include <bits/stdc++.h>

typedef long long LL;

const int N = 2e3, M = 4e6, MOD = 1e9 + 7;

int n, k, f[N + 5][N + 5], fac[M + 5], ifac[M + 5];

inline void add(int &x, const int &y) {
	(x += y) >= MOD && (x -= MOD);
}
inline int pow(int x, int k) {
	int ans = 1;
	for (; k > 0; k >>= 1, x = (LL)x * x % MOD) {
		if (k & 1) {
			ans = (LL)ans * x % MOD;
		}
	}
	return ans;
}
inline int inv(int x) {
	return pow(x, MOD - 2);
}
void init(int n) {
	fac[0] = 1;
	for (int i = 1; i <= n; i++) {
		fac[i] = (LL)fac[i - 1] * i % MOD;
	}
	ifac[n] = inv(fac[n]);
	for (int i = n; i >= 1; i--) {
		ifac[i - 1] = (LL)ifac[i] * i % MOD;
	}
}
inline int binom(int n, int m) {
	return (LL)fac[n] * ifac[m] % MOD * ifac[n - m] % MOD;
}
int main() {
	scanf("%d%d", &n, &k);
	if (k == 1) {
		printf("1\n");
		return 0;
	}
	init(n * k);
	f[0][0] = 1;
	for (int i = 0; i <= n; i++) {
		for (int j = 0; j <= n && j <= i; j++) {
			if (i < n) {
				add(f[i + 1][j], f[i][j]);
			}
			if (j < n) {
				add(f[i][j + 1], (LL)f[i][j] * (n - j) % MOD * binom(n * k - i - j * (k - 1) - 1, k - 2) % MOD);
			}
		}
	}
	printf("%d\n", f[n][n]);
	return 0;
}