/*
ID: varunra2
LANG: C++
TASK: kangaroooo
*/
#include <bits/stdc++.h>
using namespace std;
#ifdef DEBUG
#include "lib/debug.h"
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#define debug_arr(...) \
cerr << "[" << #__VA_ARGS__ << "]:", debug_arr(__VA_ARGS__)
#pragma GCC diagnostic ignored "-Wsign-compare"
//#pragma GCC diagnostic ignored "-Wunused-parameter"
//#pragma GCC diagnostic ignored "-Wunused-variable"
#else
#define debug(...) 42
#endif
#define EPS 1e-9
#define IN(A, B, C) assert(B <= A && A <= C)
#define INF (int)1e9
#define MEM(a, b) memset(a, (b), sizeof(a))
#define MOD 1000000007
#define MP make_pair
#define PB push_back
#define all(cont) cont.begin(), cont.end()
#define rall(cont) cont.end(), cont.begin()
#define x first
#define y second
const double PI = acos(-1.0);
typedef long long ll;
typedef long double ld;
typedef pair<int, int> PII;
typedef map<int, int> MPII;
typedef multiset<int> MSETI;
typedef set<int> SETI;
typedef set<string> SETS;
typedef vector<int> VI;
typedef vector<PII> VII;
typedef vector<VI> VVI;
typedef vector<string> VS;
#define rep(i, a, b) for (int i = a; i < (b); ++i)
#define trav(a, x) for (auto& a : x)
#define sz(x) (int)(x).size()
typedef pair<int, int> pii;
typedef vector<int> vi;
#pragma GCC diagnostic ignored "-Wsign-compare"
// util functions
const int N = 2005;
ll dp[N][N];
int main() {
// #ifndef ONLINE_JUDGE
// freopen("kangaroooo.in", "r", stdin);
// freopen("kangaroooo.out", "w", stdout);
// #endif
cin.sync_with_stdio(0);
cin.tie(0);
int n, a, b;
cin >> n >> a >> b;
dp[1][1] = 1;
for (int i = 2; i <= n; i++) {
for (int j = 1; j <= n; j++) {
if (i == a or i == b)
dp[i][j] = (dp[i - 1][j - 1] + dp[i - 1][j]) % MOD;
else {
dp[i][j] = dp[i - 1][j + 1] * j;
dp[i][j] += dp[i - 1][j - 1] * (max(0, (j - (i > a) - (i > b))));
dp[i][j] %= MOD;
}
}
}
cout << dp[n][1] << '\n';
return 0;
}
