My solution to https://icpcarchive.ecs.baylor.edu/external/37/3774.pdf

Taunting.java

import java.util.*;
import java.lang.*;

public class Taunting {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);

        while (scan.hasNextInt()) {
            double thisx = 0;
            double thisy = 0;
            double size = 0;

            int n = scan.nextInt();
            scan.nextLine();

            String line = scan.nextLine();
            String[] parts = line.split(",");
            double firstx = Double.parseDouble(parts[0]);
            double firsty = Double.parseDouble(parts[1]);

            double previousx = firstx;
            double previousy = firsty;

            for (int i = 2; i <= n; i++) {
                line = scan.nextLine();
                parts = line.split(",");
                thisx = Double.parseDouble(parts[0]);
                thisy = Double.parseDouble(parts[1]);

                double miny = thisy;
                double maxy = previousy;
                if (previousy < thisy) {
                    miny = previousy;
                    maxy = thisy;
                }

                double timedelta = thisx - previousx;

                size += (timedelta * miny) + (timedelta * (maxy-miny) * 0.5);

                previousx = thisx;
                previousy = thisy;
            }

            System.out.printf("%.2f to %.2f: %.4f\n", firstx, thisx, size);
        }
    }
}