#include <bits/stdc++.h>
using namespace std;
const int MAXN = 2005;
const int MOD = 1e9 + 7;
int add(int a, int b){ return (a + b >= MOD) ? a + b - MOD : a + b; }
int sub(int a, int b){ return (a - b < 0) ? a - b + MOD : a - b; }
int mul(int a, int b){ return (long long) a * b % MOD; }
int n, s, f, dp[MAXN][MAXN];
int main(){
cin >> n >> s >> f;
if(s > f) swap(s, f);
dp[0][0] = 1;
for(int i = 1; i <= n; ++i){
for(int j = 1; j <= i; ++j){
if(max(s, f) <= i && i < n && j == 1) continue;
int choose = mul(j, j + 1);
if(s < i && i < f) choose = sub(choose, j);
else if(f < i){
choose = sub(choose, 2 * j);
if(i == n) choose = 1;
}
else if(i == s) choose = j;
else if(i == f){
if(i == n) choose = 1;
else choose = j - 1;
}
if(i == s || i == f){
dp[i][j] = add(dp[i - 1][j - 1], mul(dp[i - 1][j], choose));
} else {
dp[i][j] = add(dp[i - 1][j - 1], mul(dp[i - 1][j + 1], choose));
}
}
}
cout << dp[n][1];
return 0;
}
