#include <bits/stdc++.h>
#define GOOD_LUCK ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define int long long
#define endl "\n"
#define ff first
#define ss second
#define pb push_back
#define all(v) v.begin(), v.end()
using namespace std;
constexpr int MAX = 2e+5 + 1, INF = 2e+16, MOD = 1e+9 + 7, K = 31;
void _() {
int n, a, b;
cin >> n >> a >> b;
vector <vector <int>> dp(n+1, vector <int>(n+2, 0));
// dp[0][0] = 1;
dp[1][1] = 1;
int x=0;
for (int i = 1; i <= n; i++) {
if (i == a) x++;
if (i == b) x++;
for (int j = 1; j <= i; j++) {
if (i == a || i == b) {
dp[i][j] += dp[i-1][j];
dp[i][j] += dp[i-1][j-1];
}
else {
dp[i][j] += dp[i-1][j-1] * (j - x);
dp[i][j] += dp[i-1][j+1] * (j - 1);
}
dp[i][j] %= MOD;
}
}
cout << dp[n][n];
}
signed main() {
GOOD_LUCK
int tests=1;
// cin >> tests;
for (int i=1; i <= tests; i++) {
_();
cout << endl;
}
return 0;
}
