#pragma GCC optimize("trapv")
#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <chrono>
#include <complex>
#include <cstdio>
#include <cstring>
#include <deque>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <memory>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <vector>
using namespace std;
#define int long long
#define all(x) begin(x), end(x)
#define sz(x) (int) (x).size()

const int mod = 1e9+7;
const int mxn = 50;
const int rmxn = 2e3;

int n, cs, cf;
int a[mxn][mxn][mxn], d[mxn][mxn][mxn];

signed main() {
	
	scanf("%lld%lld%lld",&n,&cs,&cf);
	if (cs > cf) swap(cs,cf);
	
	a[2][1][2] = 1;
	d[2][2][1] = 1;
		
	for (int k = 3; k < mxn; k++) {
		for (int i = 1; i <= k; i++) {
			for (int j = i+1; j <= k; j++) {
				
				for (int x = i; x <= k-1; x++) {
					a[k][i][j] += d[k-1][x][j-1];
					a[k][i][j] %= mod;
				}
				for (int x = 1; x < i; x++) {
					d[k][i][j] += a[k-1][x][j-1];
					d[k][i][j] %= mod;
				}
				
			}
			for (int j = 1; j < i; j++) {
				a[k][i][j] = d[k][k+1-i][k+1-j];
				d[k][i][j] = a[k][k+1-i][k+1-j];
			}
		}
	}
	
	printf("%lld",(a[n][cs][cf]+d[n][cs][cf])%mod);
	
	return 0;
}