import java.util.Scanner;
public class Main {
public static void main(String[] args){
Scanner in = new Scanner(System.in);
int target = in.nextInt();
int[] sale = new int[100001];
int first = in.nextInt();
int fir = in.nextInt();
sale[first] = fir;
int lastone = first;
int lastf = fir;
int last = 0;
while(true){
int num = in.nextInt();
int nex = in.nextInt();
if( num == -1 && nex == -1 ) break;
for( int i = lastone+1 ; i < num ; i++ ){
sale[i] = sale[lastone] + ( nex-sale[lastone] )*(i-lastone)/(num-lastone);
}
sale[num] = nex;
last = num;
lastone = n