#include <bits/stdc++.h>
using namespace std;
int n, cs, cf;
int F(int i, bool dir, vector<bool> vis, int vcnt) {
vis[i] = 1;
vcnt++;
int result = 0;
if (vcnt == n) return i == cf;
if (dir) {
for (int j = i + 1; j < n; j++) {
if (!vis[j]) result += F(j, 0, vis, vcnt);
}
} else {
for (int j = i - 1; j >= 0; j--) {
if (!vis[j]) result += F(j, 1, vis, vcnt);
}
}
return result;
}
int32_t main() {
ifstream fin("kangoroo.in");
ofstream fout("kangoroo.out");
fin >> n >> cs >> cf;
cs--, cf--;
vector<bool> vis(n);
fout << F(cs, 0, vis, 0) + F(cs, 1, vis, 0) << "\n";
}
