#include <bits/stdc++.h>

using namespace std;

#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define RFOR(i, a, b) for(int i = (a) - 1; i >= (b); i--)
#define SZ(a) int(a.size())
#define ALL(a) a.begin(), a.end()
#define PB push_back
#define MP make_pair
#define F first
#define S second

typedef long long LL;
typedef vector<int> VI;
typedef pair<int, int> PII;
typedef double db;

int t, n, b;

void solve()
{
	vector<pair<db, int>> allFiles(t);
	for (auto& [s, p] : allFiles)
	{
		cin >> s >> p;
		p = 100 - p;
	}
	sort(ALL(allFiles));
	vector<db> curFiles;
	int ptr = 0;
	while (ptr < min(n, t))
	{
		auto [s, p] = allFiles[ptr++];
		curFiles.PB(p / 100.0 * s);
	}
	db ans = 0;
	while (!curFiles.empty())
	{
		auto it = min_element(ALL(curFiles));
		db mn = *it;
		ans += mn / b * SZ(curFiles);
		curFiles.erase(it);
		for (db& x : curFiles)
			x -= mn;
		if (ptr < t)
		{
			auto [s, p] = allFiles[ptr++];
			curFiles.PB(p / 100.0 * s);
		}
	}
	cout << ans << "\n" << "\n";
}

int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout << fixed << setprecision(2);
	for (int tc = 1; ; tc++)
	{
		cin >> t >> n >> b;
		if (t == 0)
			return 0;
		cout << "Case " << tc << ": ";
		solve();
	}
	return 0;
}