#include <iostream>
#include <iomanip>
#include <cstdio>
using namespace std;

const int MAXCARS = 100;
const bool DEBUG = false;
const double EPS = 0.0000001;

struct car {
	double l;
	int s;
} cars[MAXCARS];

double roundUp(double d)
{
	int id = (int)(4*d + 1.0 - EPS);
	return id/4.0;
}

double roundDown(double d)
{
	int id = (int)(4*d + EPS);
	return id/4.0;
}

double getNextTime(double time, double l, int s, int n)
{
	double ans = 0.0;
	double intTime;

	for(int i=0; i<n; i++) {
//cout << "Car " << i << ", speed = " << cars[i].s << ", my speed = " << s << endl;
		if (cars[i].s == s)
			continue;
//cout << "here, car #" << i << endl;
		if (cars[i].l <= l && cars[i].s < s) {
			intTime = roundDown((l-1 - cars[i].l)/(cars[i].s - s));	// time to intersect back of car
			if (intTime > 0.0)
				intTime = 0.25;
		}
		else if (cars[i].l >= l-1 && cars[i].s > s) {
			intTime = roundDown((l - cars[i].l)/(cars[i].s - s));		// time to intersect front of car
			if (intTime > 0.0)
				intTime = 0.25;
		}
		else if (cars[i].s > s) 
			intTime = roundUp((l-1 - cars[i].l)/(cars[i].s - s));	// time to intersect back of car
		else
			intTime = roundUp((l - cars[i].l)/(cars[i].s - s));		// time to intersect front of car
if (DEBUG) { cout << "car " << i << " intersect time = " << setprecision(10) << intTime << endl; }
		if (intTime > 0.0) {
if (DEBUG) { cout << "   updated to  " << intTime << endl; }
			if (ans == 0.0 || intTime < ans) {
					ans = intTime;
if (DEBUG) cout << "  update next intersection time!" << endl;
			}
		}
	}
if (DEBUG) {
cout << "next intersection at time = " << ans+time << endl;;
}
	return ans + time;
}

double calcNextLoc(double currTime, double nextTime, double currLoc, int speed)
{
	return currLoc + (nextTime-currTime)*speed;
}

int main()
{
	int s, d, icase = 0;
	double l;
	int n;
	cin >> l >> s >> d >> n;
	double time = 0.0;
	while (l != 0 || s != 0) {
		icase++;
		double newSpeed = s;
		int num = 1;
		for(int i=0; i<n; i++) {
			cin >> cars[i].l >> cars[i].s;
			if (cars[i].l >= l-1 && cars[i].l <= l) {
				num++;
				newSpeed += cars[i].s;
			}
		}
		if (num > 1)
			s = newSpeed/num;
		while (true) {
			double currtime = time;
			time += (d-l)/s;				// time to get to destination at current speed

			double nextTime = getNextTime(currtime, l, s, n);		// get next intersection time
			if (nextTime == currtime) {
//				cout << "This should never happen" << endl;
				break;
			}
			double nextLoc = calcNextLoc(currtime, nextTime, l, s);	// check if intersection happens
			if (nextTime > time || nextLoc > d) {					//   after car reaches dest
				break;
			}
			newSpeed = s;
			num = 1;
												// determine which cars are next to Anna's car
			for(int i=0; i<n; i++) {
				cars[i].l = calcNextLoc(currtime, nextTime, cars[i].l, cars[i].s);
if (DEBUG) {
cout << "car " << i << " located at " << cars[i].l << " at time " << nextTime << " with speed " << cars[i].s << endl;
cout << "    difference = " << nextLoc - cars[i].l << endl;
}
				if (cars[i].l <= nextLoc && cars[i].l >= nextLoc-1) {
					newSpeed = newSpeed + cars[i].s;
					num++;
				}
			}
			s = newSpeed/num;
			l = nextLoc;
			time = nextTime;
if (DEBUG) {
cout << "speed changed to " << s;
cout << " at location " << l;
cout << " at time " << time << endl << endl;
}
			if (nextLoc == d)
				break;
		}
		cout << "Case " << icase << ": ";
//		cout << "Anna reaches her destination at time " << time;
//		cout << " at a speed of " << s << endl;
		printf("Anna reaches her destination at time %.4f at a speed of %d\n", time, s); 
			
		cin >> l >> s >> d >> n;
		time = 0.0;
	}
}