#include <bits/stdc++.h>
#define MAX 2005
using ll = long long;
ll tab[MAX][MAX];
bool existe[MAX][MAX];
int N,A,B;
ll MOD = 1e9+7;
ll dp(ll C,ll K){
// std::cout<<C<<" "<<K<<"\n";
if(K==N){
return (C==1);
}
ll P = (K>A)+(K>B);
if(existe[C][K])return tab[C][K];
existe[C][K]=1;
if(K==A||K==B){
// std::cout<<"yeah\n";
int permite=0;
if(K==N-1)permite=1;
ll aumenta = dp(C,K+1)*(C-P+permite);
ll cria = dp(C+1,K+1);
return tab[C][K]=(aumenta+cria)%MOD;
}else {
if(K==N-1){
if(C!=2)return 0;
return tab[C][K]=dp(C-1,K+1);
}
ll une = 0;
if(C){
une=dp(C-1,K+1)*(C-P)*(C-1);
}
ll cria = dp(C+1,K+1);
return tab[C][K]=(une+cria)%MOD;
}
}
int main()
{
std::cin>>N>>A>>B;--A;--B;
std::cout<<dp(0,0)<<"\n";
}
