#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#define fi first
#define se second
#define ll long long
#define pb push_back
#define ii pair<int,int>
template <class T>
using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
const int nax=2e3+5;
const int MOD=1e9+7;
#define optimise ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
long long dp[nax][nax];
int main()
{
optimise;
int n,s,t;
cin>>n>>s>>t;
if(n<=2){
cout <<0<<endl;
return 0;
}
if(s>t) swap(s,t);
memset(dp,0,sizeof dp);
dp[0][0] = 1;
for (int i = 1; i <= n; ++i)
{
for (int j = 0; j <= n-i+1; ++j)
{
if(i<s){
dp[i][j]+= 1ll * dp[i-1][j+1] * (j+1) * (j);
dp[i][j]+= (j ? dp[i-1][j-1] : 0);
}else if(i==s){
dp[i][j]+= 1ll * dp[i-1][j+1] * (j+1);
dp[i][j]+= dp[i-1][j];
}else if(i<t){
dp[i][j]+= 1ll * dp[i-1][j+1] * (j+1) * (j+1);
dp[i][j]+= (j ? dp[i-1][j-1] : 0);
}else if(i==t){
dp[i][j]+= 1ll* dp[i-1][j+1] * (j+1);
dp[i][j]+= dp[i-1][j];
}else if(i>t){
dp[i][j]+= 1ll * dp[i-1][j+1] * (j+2) * (j+1);
dp[i][j]+= (j ? dp[i-1][j-1] : 0);
}
dp[i][j]%=MOD;
}
}
cout <<dp[n-1][0]<<endl;
}
