#include <bits/stdc++.h> using namespace std; #define int long long const int sz = 2005; int n, cs, cf, cnt; bool used[sz]; void dfs(int rm, int u, bool pre) { if(u == cf) { if(!rm) cnt++; return; } if(!rm) return; used[u] = 1; if(u == cs) { for(int to = 1;to <= n;to++) { if(used[to]) continue; dfs(rm-1, to, (to > u)); } return; } if(!pre) { for(int to = u+1;to <= n;to++) { if(used[to]) continue; dfs(rm-1, to, 1); } } else { for(int to = 1;to < u;to++) { if(used[to]) continue; dfs(rm-1, to, 0); } } used[u] = 0; } signed main() { ios_base::sync_with_stdio(0); cout.tie(0); cin >> n >> cs >> cf; dfs(n-1, cs, 0); cout << cnt << "\n"; }