http://poj.org/problem?id=1113
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class Main {
class Point {
int x;
int y;
public Point(int x, int y) {
this.x = x;
this.y = y;
}
}
public static void main(String[] args) throws IOException {
Main main = new Main();
BufferedReader read = new BufferedReader(new InputStreamReader(
System.in));
String[] s;
s = read.readLine().split(" ");
int n = Integer.parseInt(s[0]);
int l = Integer.parseInt(s[1]);
int x, y;
Point[] p = new Point[n];
for (int i = 0; i < n; i++) {
s = read.readLine().split(" ");
x = Integer.parseInt(s[0]);
y = Integer.parseInt(s[1]);
p[i] = main.new Point(x, y);
}
Point[] ch = new Point[n];
int len = 0;
if (n >= 3) {
len = Graham_scan(p, ch, n);
}
double sum = 0;
for (int i = 0; i < len - 1; i++) {
sum += distance(ch[i], ch[i + 1]);
}
if (len > 1) {
sum += distance(ch[len - 1], ch[0]);
}
sum += 2 * l * Math.PI;
System.out.println(Math.round(sum));
}
public static double multiply(Point p1, Point p2, Point p0) {
return ((p1.x - p0.x) * (p2.y - p0.y) - (p2.x - p0.x) * (p1.y - p0.y));
}
public static double distance(Point p1, Point p2) {
return (Math.sqrt((p1.x - p2.x) * (p1.x - p2.x) + (p1.y - p2.y)
* (p1.y - p2.y)));
}
public static int Graham_scan(Point[] PointSet, Point[] ch, int n) {
int i, j, k = 0, top = 2;
Point tmp;
for (i = 1; i < n; i++)
if ((PointSet[i].y < PointSet[k].y)
|| ((PointSet[i].y == PointSet[k].y) && (PointSet[i].x < PointSet[k].x)))
k = i;
tmp = PointSet[0];
PointSet[0] = PointSet[k];
PointSet[k] = tmp;
for (i = 1; i < n - 1; i++) {
k = i;
for (j = i + 1; j < n; j++)
if ((multiply(PointSet[j], PointSet[k], PointSet[0]) > 0)
|| ((multiply(PointSet[j], PointSet[k], PointSet[0]) == 0) && (distance(
PointSet[0], PointSet[j]) < distance(
PointSet[0], PointSet[k]))))
k = j;
tmp = PointSet[i];
PointSet[i] = PointSet[k];
PointSet[k] = tmp;
}
ch[0] = PointSet[0];
ch[1] = PointSet[1];
ch[2] = PointSet[2];
for (i = 3; i < n; i++) {
while (top > 0 && multiply(PointSet[i], ch[top], ch[top - 1]) >= 0)
top--;
ch[++top] = PointSet[i];
}
return top + 1;
}
}