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  1.  
  2. import java.io.*;
  3. import java.util.*;
  4.  
  5. public class CarefulWithPoison {
  6.  
  7. 	static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
  8. 	static PrintWriter out = new PrintWriter(new BufferedOutputStream(System.out));
  9. 	static StringTokenizer st = new StringTokenizer("");
  10.  
  11. 	public static String next() {
  12. 		try	{
  13. 		while (!st.hasMoreTokens()) {
  14. 			String s = br.readLine();
  15. 			if (s == null)
  16. 				return null;
  17. 			st = new StringTokenizer(s);
  18. 		}
  19. 		return st.nextToken();
  20. 		}	catch(Exception e)	{
  21. 			return	null;
  22. 		}
  23. 	}
  24. 	public static void main(String[] asda) throws Exception {
  25. 		int max = 2000000 + 10;
  26. 		fact = new long [max];
  27. 		fact[0] = fact[1] = 1;
  28. 		for (int k = 2; k < max; k++)	{
  29. 			fact[k] = (k * fact[k-1]) % MOD;
  30. 		}
  31.  
  32. 		while	(true)	{
  33. 			int N = Integer.parseInt( next() );
  34. 			if (N == 0) {
  35. 				break;
  36. 			}
  37. 			int a = Integer.parseInt( next() );
  38. 			int b = Integer.parseInt( next() );
  39. 			long A = ways(N+N, N);
  40. 			long B = count(N, a+2, b);
  41. 			long C = count(N, a+1, b+1);
  42. 			long D = count(N, a, b+2);
  43.  
  44. 			long ans = (A - ((B+C+D)%MOD) + MOD) % MOD;
  45. 			out.println(ans);
  46. 		}
  47.         //
  48.         out.flush();
  49.         System.exit(0);
  50.     }
  51.     static long [] fact;
  52.     static long MOD = 1000000007;
  53.  
  54.     static long count(int N, int a, int b)	{
  55.     	return	(ways(a+b, a) * ways(N - a + N - b, N - a)) % MOD;
  56.     }
  57.     static long ways(int N, int K)	{
  58.     	long ans = fact[N] * modInverse( fact[K] );
  59.     	ans %= MOD;
  60.     	ans *= modInverse( fact[N-K] );
  61.     	return	ans % MOD;
  62.     }
  63.  
  64.     static long modInverse(long x)	{
  65. 		return	modPow( x, MOD - 2, MOD );
  66. 	}
  67.     static long modPow(long x, long pow, long mod)	{
  68. 		long res = 1;
  69. 		while	( pow > 0 )	{
  70. 			if	( (pow&1) != 0 )	res = (res * x) % mod;
  71. 			pow >>= 1;
  72. 			x = (x*x) % mod;
  73. 		}
  74. 		return res;
  75. 	}
  76. }
  77.  
Compilation error #stdin compilation error #stdout 0s 0KB
comments (?)
stdin
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Standard input is empty
compilation info 
Main.java:5: error: class CarefulWithPoison is public, should be declared in a file named CarefulWithPoison.java
public class CarefulWithPoison {
       ^
1 error
stdout
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Standard output is empty
https://ideone.com/sHX78N
language:
Java (HotSpot 12)
created:
9 years ago
visibility:
secret

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