import java.util.ArrayList;
import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;
import javax.swing.text.html.HTMLDocument.Iterator;
public class Joy{
public static void main(String[] args) {
Scanner reader = new Scanner(System.in);
int pairs = Integer.parseInt(reader.nextLine());
ArrayList<Integer> distances = new ArrayList<Integer>();
while(pairs != -1){
int distance = 0;
int hours = 0;
for(int i = 0; i < pairs; i++){
String[] temp = reader.nextLine().split(" ");
distance += Integer.parseInt(temp[0]) * (Integer.parseInt(temp[1]) - hours);
hours = Integer.parseInt(temp[1]);
}
distances.add(distance);
pairs = Integer.parseInt(reader.nextLine());
}
for(int i = 0; i < distances.size(); i++){
System.out.println(distances.get(i) + " miles");
}
reader.close();
}
}