#include <bits/stdc++.h>
#define all(x) (x).begin(),(x).end()
using namespace std;
using ll = long long;
// #define int ll
#define sz(x) ((int)(x).size())
const int nmax = 2e3 + 5;
const int mod = 1e9 + 7;
struct Mint {
int val;
Mint(ll x = 0): val((x % mod + mod) % mod) {;}
Mint operator +(const Mint& x) const { return Mint(val + x.val); }
Mint operator -(const Mint& x) const { return Mint(val - x.val); }
Mint operator *(const Mint& x) const { return Mint((ll)val * x.val); }
Mint operator +=(const Mint& x) { return *this = Mint(val + x.val); }
Mint operator -=(const Mint& x) { return *this = Mint(val - x.val); }
Mint operator *=(const Mint& x) { return *this = Mint((ll)val * x.val); }
Mint operator ^(int b) const {
Mint accum = 1, a = *this;
while(b) {
accum = (b & 1? accum * a : accum);
a *= a;
b >>= 1;
}
return accum;
}
Mint operator /(const Mint& x) { return Mint((ll)val * (x ^ (mod - 2)).val); }
Mint operator /=(const Mint& x) { return *this = Mint((ll)val * (x ^ (mod - 2)).val); }
};
Mint dp[nmax][nmax][2][2];
signed main() {
int N, S, T;
cin >> N >> S >> T;
vector<int> initial(3);
iota(all(initial), 1);
do {
if(S <= 3 && initial[0] != S) continue;
if(T <= 3 && initial.back() != T) continue;
// for(auto x : initial) cerr << x << ' ';
// cerr << '\n';
dp[3][(initial[1] > initial[0]) && (initial[2] < initial[1])][initial[1] > initial[0]][initial[2] > initial[1]] += 1;
} while(next_permutation(all(initial)));
for(int len = 3; len <= N; len++) {
int stanga = (len + 1 <= S && len + 1 != T), dreapta = (len + 1 <= T && len + 1 != S), inside = (len + 1 != T && len + 1 != S);
for(int stand = 0; stand <= len - 2; stand++) {
for(int lval = 0; lval < 2; lval++) {
for(int rval = 0; rval < 2; rval++) {
int eq = (len - 2) - (lval == rval? stand * 2 : (lval == 1? stand * 2 - 1 : stand * 2 + 1));
if(eq < 0) continue;
if(inside) {
if(lval == 0) // append 1 la inceput (deci 10 nou si restul la fel) (prin 0, i.e. pui pe a doua pozitie)
dp[len + 1][stand + 1][1][rval] += dp[len][stand][0][rval];
if(lval == 1); // asta e de inside, nu se poate intampla nimic ce nu e legat de standard/equaluri
if(rval == 0); // aceeasi poveste, incat insereaza inauntru (deci e legat de stand/eq)
if(rval == 1) // a doua pozitie, devine 10
dp[len + 1][stand + 1][lval][0] += dp[len][stand][lval][1];
// stand devine eq (in doua moduri)
dp[len + 1][stand][lval][rval] += dp[len][stand][lval][rval] * stand * 2;
// equal devine stand
dp[len + 1][stand + 1][lval][rval] += dp[len][stand][lval][rval] * eq;
}
if(stanga) {
dp[len + 1][stand][0][rval] += dp[len][stand][lval][rval];
}
if(dreapta) {
dp[len + 1][stand][lval][1] += dp[len][stand][lval][rval];
}
}
}
}
}
Mint sum = 0;
for(int len = N; len <= N; len++) {
for(int stand = 0; stand <= N; stand++) {
for(int lval = 0; lval < 2; lval++) {
for(int rval = 0; rval < 2; rval++) {
int eq = (len - 2) - (lval == rval? stand * 2 : (lval == 1? stand * 2 - 1 : stand * 2 + 1));
if(eq == 0)
cerr << len << ' ' << stand << ' ' << lval << ' ' << rval << '\n',
sum += dp[len][stand][lval][rval];
}
}
}
}
cout << sum.val << '\n';
}
