import java.util.*; import java.util.zip.*; import java.util.List; import java.util.regex.*; import java.util.concurrent.*; import java.util.concurrent.atomic.*; import java.util.concurrent.locks.*; import java.util.function.*; import javax.swing.*; import javax.swing.event.*; import javax.swing.text.*; import javax.swing.table.*; import java.io.*; import java.net.*; import java.lang.reflect.*; import java.lang.ref.*; import java.lang.management.*; import java.security.*; import java.security.spec.*; import java.awt.*; import java.awt.event.*; import java.awt.image.*; import java.awt.geom.*; import javax.imageio.*; import java.math.*; import java.time.Duration; // angle between p2-p1 and the x axis (?) class main { static double twoPointAngle(IDoublePt p1, IDoublePt p2) { return atan2( p2.x_double()-p1.x_double(), p2.y_double()-p1.y_double()); } static double atan2(double x, double y) { return Math.atan2(x, y); } interface IDoublePt { public double x_double(); public double y_double(); } }