#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <chrono>
#include <complex>
#include <cstdio>
#include <cstring>
#include <deque>
#include <iomanip>
#include <iterator>
#include <list>
#include <map>
#include <memory>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <vector>
using namespace std;
#define int long long
#define all(x) begin(x), end(x)
#define sz(x) (int) (x).size()

const int mod = 1e9+7;
const int mxn = 2e3+5;

int n, cs, cf, dp[mxn][mxn];


signed main() {
	scanf("%lld%lld%lld",&n,&cs,&cf);
	dp[1][1]=1;
	for (int i=2; i<=n; i++) {
		for (int j=1; j<=i; j++) {
			if (i==cs || i==cf) {
				dp[i][j] = (dp[i-1][j-1] + dp[i-1][j])%mod;
			} else {
				int ptk = (i>cs) + (i>cf);
				int ip = j-ptk;
				dp[i][j] = (dp[i-1][j-1]*ip + dp[i-1][j+1]*j)%mod;
			}
		}
	}
	printf("%lld",dp[n][1]);
}