#include <bits/stdc++.h>
#pragma GCC target("avx2")
#pragma GCC optimize("O3,unroll-loops")
using namespace std;
#define int long long
#define pii pair<int,int>
#define ff first
#define ss second
#define sp << " " <<
#define all(cont) cont.begin(),cont.end()
#define vi vector<int>
const int inf = 1e17,N = 3e5+1,MOD = 1e9+7,BL = 1000;
int add(int x,int y) {
return ((x+y >= MOD) ? (x+y-MOD) : x+y);
}
int mult(int x,int y) {
return (x*y)%MOD;
}
void solve() {
int n,a,b;
cin >> n >> a >> b;
int dp[n+1][n+1]{};
dp[0][0] = 1;
for (int i=0;i<=n;i++) {
for (int j = 0;j<n;j++) {
if (!dp[i][j]) continue;
if (i==n) continue;
dp[i+1][j+1] = add(dp[i+1][j+1],dp[i][j]);
if (i != a-1 && i != b-1) {
int select;
if (i >= a-1 && i >= b-1) select = (j-2)*(j-3)+2*(j-2)+(i == n-1 && j == 2);
else if (i >= a-1 || i >= b-1) select = (j-1)*(j-1);
else select = j*(j-1);
dp[i+1][j-1] = add(dp[i+1][j-1],mult(dp[i][j],select));
}
else if (i == a-1) {
dp[i+1][j] = add(dp[i+1][j],mult(dp[i][j],j-(i >= b-1 && i != n-1)));
}
else {
dp[i+1][j] = add(dp[i+1][j],mult(dp[i][j],j-(i >= a-1 && i != n-1)));
}
}
}
cout << dp[n][1] << '\n';
}
int32_t main() {
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#ifdef Dodi
freopen("in.txt","r",stdin);
freopen("out.txt","w",stdout);
#endif
int t = 1;
//cin >> t;
while (t --> 0) solve();
}
