#include <bits/stdc++.h>
using namespace std;
#define all(x) begin(x), end(x)
#define sz(x) ((int)size(x))
#define trace(x) cout << #x << ": " << (x) << endl;
typedef long long ll;
const int mod = 1'000'000'007, maxN = 2001;
int add(int a, int b) {
return a + b < mod ? a + b : a + b - mod;
}
int mul(int a, int b) {
return a * (ll) b % mod;
}
int dp[maxN][maxN];
//dp[i][number of blocks]
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int N, S, T;
cin >> N >> S >> T;
dp[1][1] = 1;
for (int i = 2; i <= N; ++i) {
for (int j = 1; j <= i; ++j) {
if (i == S || i == T) {
dp[i][j] = add(dp[i - 1][j - 1], dp[i - 1][j]);
} else {
dp[i][j] = add(mul(dp[i - 1][j - 1], j - (S < i) - (T < i)), mul(dp[i - 1][j + 1], j));
}
}
}
cout << dp[N][1];
return 0;
}
