#include<bits/stdc++.h>
using namespace std;
typedef long long llint;
const int MAXN = 5005;
const int MOD = 1000000007;
int n, x, y;
llint dp[MAXN][MAXN];
int main () {
cin >> n >> x >> y;
if (x > y) swap(x, y);
dp[n+1][0] = 1;
for (llint i = n; i >= 1; i--) {
for (llint g = 1; g <= n; g++) {
if (y < i) dp[i][g] = (dp[i+1][g-1] + (g+1) * g % MOD * dp[i+1][g+1] % MOD) % MOD;
if (i == y) dp[i][g] = (dp[i+1][g-1] + g * dp[i+1][g] % MOD) % MOD;
if (x < i && i < y) dp[i][g] = (dp[i+1][g-1] + g * g % MOD * dp[i+1][g+1] % MOD) % MOD;
if (i == x) dp[i][g] = (dp[i+1][g-1] + (g-1) * dp[i+1][g] % MOD) % MOD;
if (i < x) dp[i][g] = (dp[i+1][g-1] + (g-1) * g % MOD * dp[i+1][g+1] % MOD) % MOD;
}
}
cout << dp[2][2];
return 0;
}
