#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 2000;
const int MOD = 1e9 + 7;
struct ZP {
int x;
ZP operator + ( ZP a ) {
return { (x + a.x) % MOD };
}
void operator += ( ZP a ) {
x = (x + a.x) % MOD;
}
ZP operator * ( ZP a ) {
return { (int)((long long)x * a.x % MOD) };
}
ZP operator * ( int a ) {
return { (int)((long long)x * a % MOD) };
}
void operator = ( int a ) {
x = a;
}
void out() {
cout << x << "\n";
}
};
ZP dp[MAX_N + 1][MAX_N + 1][2][2];
int main() {
int n, s, f;
cin >> n >> s >> f;
if ( s > f )
swap( s, f );
if ( s == 1 ) {
if ( f == 2 )
dp[3][1][1][1] = 1;
dp[2][0][1][0] = 1;
} else
dp[1][0][0][0] = 1;
int p = 2;
for ( int i = 0; i < s - 1; i++ ) {
for ( int mx = 0; mx <= n; mx++ ) {
dp[i + 1][mx][0][0] += dp[i][mx][0][0] * (mx * 2 + 2);
dp[i + 1][mx + 1][0][0] += dp[i][mx][0][0] * (p - 2 - mx * 2);
}
if ( i == 0 && s > 1 )
p--;
p++;
}
for ( int mx = 0; mx <= n; mx++ ) {
dp[s][mx][0][0] = dp[s - 1][mx][0][0];
dp[s][mx][0][1] = dp[s - 1][mx][0][1];
dp[s][mx][1][0] = dp[s - 1][mx][1][0];
dp[s][mx][1][1] = dp[s - 1][mx][1][1];
}
for ( int i = s; i < f - 1; i++ ) {
for ( int mx = 0; mx <= n; mx++ ) {
dp[i + 1][mx][0][0] += dp[i][mx][0][0] * (mx * 2 + 1);
dp[i + 1][mx + 1][0][0] += dp[i][mx][0][0] * (p - 2 - mx * 2);
dp[i + 1][mx + 1][1][0] += dp[i][mx][0][0];
dp[i + 1][mx][1][0] += dp[i][mx][1][0] * (mx * 2 + 1);
dp[i + 1][mx + 1][1][0] += dp[i][mx][1][0] * (p - 1 - mx * 2);
}
if ( s == 1 && i == s )
p--;
p++;
}
for ( int mx = 0; mx <= n; mx++ ) {
dp[f][mx][0][0] = dp[f - 1][mx][0][0];
dp[f][mx][0][1] = dp[f - 1][mx][0][1];
dp[f][mx][1][0] = dp[f - 1][mx][1][0];
dp[f][mx][1][1] = dp[f - 1][mx][1][1];
}
for ( int i = f; i < n; i++ ) {
for ( int mx = 0; mx <= n; mx++ ) {
dp[i + 1][mx][0][0] += dp[i][mx][0][0] * mx * 2;
dp[i + 1][mx + 1][0][0] += dp[i][mx][0][0] * (p - 2 - mx * 2);
dp[i + 1][mx + 1][1][0] += dp[i][mx][0][0];
dp[i + 1][mx + 1][0][1] += dp[i][mx][0][0];
dp[i + 1][mx][1][0] += dp[i][mx][1][0] * mx * 2;
dp[i + 1][mx + 1][1][0] += dp[i][mx][1][0] * (p - 1 - mx * 2);
dp[i + 1][mx + 1][1][1] += dp[i][mx][1][0];
dp[i + 1][mx][0][1] += dp[i][mx][0][1] * mx * 2;
dp[i + 1][mx + 1][0][1] += dp[i][mx][0][1] * (p - 1 - mx * 2);
dp[i + 1][mx + 1][1][1] += dp[i][mx][0][1];
dp[i + 1][mx][1][1] += dp[i][mx][1][1] * mx * 2;
dp[i + 1][mx + 1][1][1] += dp[i][mx][1][1] * (p - mx * 2);
}
if ( f == 2 && i == f )
p--;
p++;
}
ZP ans;
if ( n % 2 == 0 )
ans = dp[n][(n - 2) / 2][0][1] + dp[n][(n - 2) / 2][1][0];
else
ans = dp[n][n - 2 - (n - 2) / 2][1][1] + dp[n][(n - 2) / 2][0][0];
ans.out();
return 0;
}
