/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	static double f(double x,double y){
		//return Math.exp(-x*x-y*y);
		return x*x+y*y;
	}
	public static void main (String[] args) throws java.lang.Exception
	{
		// your code goes here
		double x,y,s=0.0,d=0.001;
		for(x=-1.0;x<=1.0;x+=d){
			for(y=-1.0;y<=1.0;y+=d){
				if(x*x+y*y<=1.0)
					s+=f(x,y)*d*d;
			}
		}
		System.out.println(s);
	}
}

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