#include <cstring>
#include <iostream>
//using namespace std;
typedef long long int ll;
int sta, end, n;
ll dp[2010][2010];
static ll MOD = 1000000007;
ll f(int i, int k){
if(k < 0) return 0;
if(i == n - 1) return k == 0;
ll ks = i > sta;
ll ke = i > end;
ll &ret = dp[i][k];
if(ret != -1) return ret;
ret = 0;
if(i == sta || i == end){
ret += f(i + 1, k);
ret += f(i + 1, k - 1)*k;
}
else{
ret += f(i + 1, k + 1);
ret += f(i + 1, k - 1)*k*(k - 1 + ks + ke);
}
return (ret %= MOD);
}
int main(){
std::cin.tie(0);
memset(dp, -1, sizeof dp);
std::ios_base::sync_with_stdio(0);
std::cin >> n >> sta >> end;
--sta, --end;
std::cout << f(0, 0) << "\n";
return 0;
}
