public class Chapter_2_practise{
	public static void main(String[] args) {
		int num=10000000;
		double[] x=new double[num];
		double[] y=new double[num];
		for(int i=0;i<x.length;i++)
		{
			x[i]=2*Math.random();
			y[i]=2*Math.random();
		}
		double count=0;
		for(int i=0;i<x.length;i++)
		   if(Math.pow(x[i]-1, 2)+Math.pow(y[i]-1, 2)<1)
			   count++;
		double pi=count/num*4;
		System.out.print("pi="+pi);
	} 
}