#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
ll n, s, f;
ll ans;
const ll mod = int(1e9) + 7;
ll dp[2010][2010];
int main()
{
cin >> n >> s >> f;
dp[0][0] = 1;
for(ll i=1; i<n; ++i){
if(i == s || i == f){
for(int j=0; j<i; ++j)
(dp[i][j] += dp[i-1][j]) %= mod;
for(int j=1; j<i; ++j)
(dp[i][j-1] += dp[i-1][j] * j % mod) %= mod;
continue;
}
for(ll j=0; j<i; ++j){
if(j >= 2){
(dp[i][j-1] += dp[i-1][j] * j % mod * (j-1) % mod) %= mod;
}
if(i >= s){
(dp[i][j-1] += dp[i-1][j] * j % mod) %= mod;
}
if(i >= f){
(dp[i][j-1] += dp[i-1][j] * j % mod) %= mod;
}
(dp[i][j+1] += dp[i-1][j]) %= mod;
}
}
cout << dp[n-1][0] << endl;
return 0;
}
