#include<bits/stdc++.h>
using namespace std;
#define int long long
int mod = 1e9+7;
int32_t main()
{
//freopen("input.txt", "r", stdin);
//freopen("output.txt", "w", stdout);
int n, a, b;
cin >> n >> a >> b;
vector<vector<int>> dp(n+1, vector<int>(n+1, 0));
dp[1][1] = 1;
int bb = 0;
if (a==1) bb++;
if (b==1) bb++;
for (int i = 2; i <= n; i++)
{
if (i==a)
{
dp[i] = vector<int>(dp[i-1]);
i++;
bb++;
}
if (i==b)
{
if (n%2==0)
{
for (int j = 2; j <= n; j++)
{
dp[i][j] += dp[i-1][j-1];
}
}
else
{
dp[i] = vector<int>(dp[i-1]);
}
i++;
bb++;
}
if (i==a)
{
dp[i] = vector<int>(dp[i-1]);
i++;
bb++;
}
if (i>n) break;
for (int j = 2; j <=n; j++)
{
dp[i][j] += dp[i-1][j-1]*(j);
dp[i][j] -= dp[i-1][j-1]*bb;
dp[i][j-1] += dp[i-1][j]*(j-1);
}
for (int j = 1; j <= n; j++) dp[i][j]%=mod;
}
int sol = dp[n][1];
dp.assign(n+1, vector<int>(n+1, 0));
dp[1][1] =1;
bb=0;
if (a==1) bb++;
if (b==1) bb++;
for (int i = 2; i <= n; i++)
{
if (i==a)
{
for (int j = 2; j <= n; j++)
{
dp[i][j] += dp[i-1][j-1];
}
i++;
bb++;
}
if (i==b)
{
if (n%2)
{
for (int j = 2; j <= n; j++)
{
dp[i][j] += dp[i-1][j-1];
}
}
else
{
dp[i] = vector<int>(dp[i-1]);
}
i++;
bb++;
}
if (i==a)
{
for (int j = 2; j <= n; j++)
{
dp[i][j] += dp[i-1][j-1];
}
i++;
bb++;
}
if (i>n) break;
for (int j = 2; j <=n; j++)
{
dp[i][j] += dp[i-1][j-1]*(j);
dp[i][j] -= dp[i-1][j-1]*bb;
dp[i][j-1] += dp[i-1][j]*(j-1);
}
for (int j = 1; j <= n; j++) dp[i][j]%=mod;
}
cout << (sol + dp[n][1])%mod;
}
