#include <bits/stdc++.h>
using namespace std;
const int N = 2005, MOD = 1e9 + 7;
int n, s, t, memo[N][N];
void add(int &a, int b) {
a = (a + b) % MOD;
return;
}
int calc(int pos, int k) {
if (pos == n + 1)
return (k == 1);
if (~memo[pos][k]) return memo[pos][k];
int ret = 0;
if (pos == s) {
add(ret, calc(pos + 1, k));
add(ret, calc(pos + 1, k + 1));
} else if (pos == t) {
add(ret, calc(pos + 1, k));
add(ret, calc(pos + 1, k + 1));
} else {
add(ret, calc(pos + 1, k + 1) * (k + 1 - (pos > s) - (pos > t)));
if (k >= 2) add(ret, calc(pos + 1, k - 1) * (k - 1));
}
return memo[pos][k] = ret;
}
int main(int argc, char const *argv[])
{
ios_base::sync_with_stdio(0); cin.tie(0);
memset(memo, -1, sizeof memo);
cin >> n >> s >> t;
cout << calc(1, 0) << endl;
return 0;
}
