#include <bits/stdc++.h>
using namespace std;
#define foru(i, a, b) for(int i = (a); i <= (b); ++i)
#define ford(i, a, b) for(int i = (a); i >= (b); --i)
#define rep(i, a) for(int i = 0; i < (a); ++i)
#define sz(a) (int)(a).size()
#define all(a) (a).begin(), (a).end()
#define bit(s, i) (((s) >> (i)) & 1)
#define ii pair <int, int>
#define fi first
#define se second
#define ll long long
#define eb emplace_back
#define pb push_back
#define __builtin_popcount __builtin_popcountll
template <class X, class Y>
bool maxi(X &x, Y y) {
if(x < y) {
x = y;
return true;
}
return false;
}
template <class X, class Y>
bool mini(X &x, Y y) {
if(x > y) {
x = y;
return true;
}
return false;
}
const int N=2222;
const int mod=1e9+7;
int n,cs,cf,dp[N][N];
inline int add(int a, int b){
a+=b; if(a>=mod) a-=mod;
return a;
}
inline int mul(int a, int b){
return (ll)a*b % mod;
}
void solve(){
cin>>n>>cs>>cf;
dp[0][0]=1;
foru(i,1,n){
if(i==cs || i==cf){
foru(j,1,i){
dp[i][j]=add(dp[i][j],add(dp[i-1][j],dp[i-1][j-1]));
}
} else{
foru(j,1,i){
dp[i][j]=add(dp[i][j],mul(dp[i-1][j+1],j));
int place = j-2+(i<cs)+(i<cf);
if(j==1) place=1;
dp[i][j]=add(dp[i][j],mul(dp[i-1][j-1],place));
}
}
}
cout<<dp[n][1]<<'\n';
}
int32_t main() {
#define task "test"
if(fopen(task".inp", "r")){
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
cin.tie(0)->sync_with_stdio(0);
int tc = 1; // cin >> tc;
foru(i, 1, tc){
solve();
}
}
