#include <bits/stdc++.h>
using namespace std;
int main() {
int n, s, t; cin >> n >> s >> t;
vector<int> r1({1});
for (int i = 2; i <= n; i++) {
vector<int> nr1(i, 0);
if (i % 2 == 0) for (int j = 1; j < i; j++) nr1[j] = r1[j-1] + nr1[j-1];
else for (int j = i-2; j >= 1; j--) nr1[j] = nr1[j+1] + r1[j];
r1 = nr1;
}
vector<vector<int>> table(n, vector<int>(n, 0));
table[0] = r1;
for (int i = 1; i < n; i++) {
if (n % 2 == 0) {
for (int j = i+1; j < n; j++) {
table[i][j] = table[i-1][j] + (table[i-1][j] - table[i-1][j-1]);
}
} else {
int pt = 1;
for (int j = i+1; j < n; j++) {
table[i][j] = table[0][pt];
pt++;
}
}
}
for (int i = 0; i < n; i++) {
for (int j = i+1; j < n; j++) {
table[j][i] = table[i][j];
}
}
// for (int i = 0; i < n; i++) {
// for (int j = 0; j < n; j++) {
// cout << table[i][j] << "\t";
// }
// cout << "\n";
// }
cout << table[s-1][t-1] << "\n";
}
