import java.io.*; import java.util.*; public class kangaroo { static int[][] X; static int v; static int[][][] dp; public static void main(String[] args)throws IOException { // TODO Auto-generated method stub BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); BufferedWriter out = new BufferedWriter(new OutputStreamWriter(System.out)); StringTokenizer st = new StringTokenizer(br.readLine()); int n = Integer.parseInt(st.nextToken()); int s = Integer.parseInt(st.nextToken()); int e = Integer.parseInt(st.nextToken()); long[][] dp = new long[n+1][n+1]; if(s>e) { int save = s; s = e; e = save; } long mod = 1000000007; dp[1][1] = 1; for(int i=2; i<=n; i++) { for(int j=1; j<=i; j++) { if(dp[i-1][j]==0)continue; if(i==s||i==e) { dp[i][j+1] = (dp[i][j+1]+dp[i-1][j])%mod; dp[i][j] = (dp[i][j]+dp[i-1][j])%mod; continue; } if(i<s) { dp[i][j+1] = (dp[i][j+1]+dp[i-1][j]*(j+1))%mod; dp[i][j-1] = (dp[i][j-1]+dp[i-1][j]*(j-1))%mod; } else if(i>s&&i<e) { dp[i][j+1] = (dp[i][j+1]+dp[i-1][j]*(j))%mod; dp[i][j-1] = (dp[i][j-1]+dp[i-1][j]*(j-1))%mod; } else { dp[i][j+1] = (dp[i][j+1]+dp[i-1][j]*(j-1))%mod; dp[i][j-1] = (dp[i][j-1]+dp[i-1][j]*(j-1))%mod; } } } System.out.println(dp[n][1]); } }