## Java problem with equation

Hi i need some help with my Java code. I cant seem to get it to work. I am trying to do the birthday paradox and my code keeps messing up and giving me "NaN". Can someone please help me?

Java Code:
```    public static void main(String []args)
{
int y;
Scanner keyboard = new Scanner(System.in); //Scanner so we can type a custom input
y = keyboard.nextInt(); //Lets the user input there speed.
if(y == 1)
{
double n, a, p, m, k; //Initaites the variable "speed"
Scanner keyboard1 = new Scanner(System.in);
System.out.println("Enter the amount of people in the room");
n = keyboard.nextDouble(); //Lets the user input there speed.
System.out.println("Enter the amount of days");
p = keyboard.nextDouble();
System.out.println("Enter the days again");
m = keyboard.nextDouble();
{
if (m < 0)
System.out.println(0.0);
double fact = 1.0;
while(m > 1)
{
fact = fact * m;
m = m - 1;
}
System.out.println("Test value: " + fact);
System.out.println("Test value: " + p);
double t = (p - n);
System.out.println("Test value T: " + t);
if (t < 0)
System.out.println(0.0);
double fact1 = 1.0;
while(t > 1)
{
fact1 = fact1 * t;
t = t - 1;
}
System.out.println("Test again: " + fact1);
double l = Math.pow(p, n);
System.out.println("Test interger: " + l);
double j = (fact1 * l);
System.out.println("Test interger: " + j);
double finish = (fact/j);
System.out.println("Final value: " + finish);
double testf = (finish*100);
System.out.println("Test finish: " + testf);

}

}

}

}```