uva 10014 - Simple calculations

import java.util.*;

public class Main10014 {

public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int t = scan.nextInt();
while(t-- > 0) {
int n = scan.nextInt();
double a0 = scan.nextDouble();
double an = scan.nextDouble();
double c, sum = 0;
for(int i=0; i<n; i++) {
c = scan.nextDouble();
sum += (n-i)*c;
}

System.out.printf("%.2f\n",((n * a0 + an - 2 * sum) / (n + 1)));
if(t != 0)
System.out.println();

}

}

}