#include <bits/stdc++.h>
#define GOOD_LUCK ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define int long long
#define itn int
#define INF 100000000
#define MOD 1000000007
#define MAX 103
#define endl "\n"
#define ff first
#define ss second
using namespace std;
int temp;
vector <vector <int>> dp(2005, vector <int>(2005));
signed main() {
GOOD_LUCK
int t;
t = 1;
// cin >> t;
while (t--) {
int n, a, b, cnt=0;
cin >> n >> a >> b;
dp[1][1] = 1;
for (int i=1; i <= n; i++) {
if (i == a || i == b) cnt++;
for (int j=1; j <= i; j++) {
if (i == a || i == b) {
dp[i][j+1] += dp[i-1][j];
dp[i][j+1] %= MOD;
dp[i][j] += dp[i-1][j];
dp[i][j] %= MOD;
}
else {
dp[i][j-1] += dp[i-1][j] * (j - 1);
dp[i][j-1] %= MOD;
dp[i][j+1] += dp[i-1][j] * (j + 1 - cnt);
dp[i][j+1] %= MOD;
}
}
}
cout << dp[n][1] % MOD;
}
return 0;
}
// Problem B
// by Ekber_Ekber
