//Author RufatM #pragma GCC optimize("Ofast") #include <bits/stdc++.h> #include <ext/pb_ds/assoc_container.hpp> #include <ext/pb_ds/tree_policy.hpp> #include <ext/pb_ds/detail/standard_policies.hpp> using namespace __gnu_pbds; using namespace std; typedef long long ll; typedef pair<int,int> pii; typedef pair<ll,ll> pll; typedef vector<int> vi; typedef vector<vector<int>> vvi; typedef vector<ll> vll; typedef vector<bool> vb; typedef vector<string> vs; #define fastio ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0); #define endl '\n' #define pb push_back #define pf push_front #define eb emplace_back #define ff first #define ss second #define all(x) begin(x),end(x) #define rall(x) rbegin(x),rend(x) #define mt19937_64 mt_rand(chrono::steady_clock::now().time_since_epoch().count()) #define ordered_set tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update> const int MOD=1000000007; const int INF=1000000007; const ll LINF=4e18; const int MAXN=100005; ll n,cs,cf; ll ans = 0; bool used[50]; void dfs(int cur,int prev,int vis){ if(vis == n){ if(cur == cf){ ans = (ans+1)%MOD; } return; } if(prev == -1){ for(int nxt=1;nxt<=n;nxt++){ if(nxt==cs){ continue; } if(used[nxt]){ continue; } used[nxt] = true; dfs(nxt,cur,vis+1); used[nxt] = false; } } else{ if(prev<cur){ for(int nxt=1;nxt<cur;nxt++){ if(used[nxt]){ continue; } used[nxt] = true; dfs(nxt,cur,vis+1); used[nxt] = false; } } else{ for(int nxt=cur+1;nxt<=n;nxt++){ if(used[nxt]){ continue; } used[nxt] = true; dfs(nxt,cur,vis+1); used[nxt] = false; } } } } signed main(){ fastio; #ifndef ONLINE_JUDGE //freopen("input.txt","r",stdin); //freopen("output.txt","w",stdout); #endif int t=1; //cin >> t; while(t--){ cin >> n >> cs >> cf; memset(used,false,sizeof(used)); used[cs] = true; dfs(cs,-1,1); cout << ans << endl; } }