/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
import java.math.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		System.out.println(getCollisionProbability(23, 365));
	}
 
	static BigDecimal getCollisionProbability(int n, int p){
		return (new BigDecimal("1")).subtract(fact(p).divide((new BigDecimal(String.valueOf(p))).pow(n).multiply(fact(p-n)), 6, RoundingMode.HALF_UP));
	}
 
	static BigDecimal fact(int n){
		if (n==1) return BigDecimal.ONE; else return fact(n-1).multiply(new BigDecimal(String.valueOf(n)));
	}
}

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