#include <bits/stdc++.h>
using namespace std;
 
int T, N; double P, H[1009], W[1009], dp[109][25252];
 
long double solve() {
	for (int i = 0; i <= N; i++) {
		for (int j = 0; j <= N * 250; j++) dp[i][j] = -1e9;
	}
	dp[0][0] = 0.0L;
	for (int i = 0; i < N; i++) {
		for (int j = 0; j <= N * 250; j++) {
			if (dp[i][j] <= -1e8) continue;
 
			dp[i + 1][j] = max(dp[i + 1][j], dp[i][j]);
			int U = j + min(H[i], W[i]);
			dp[i + 1][U] = max(1.0L*dp[i + 1][U], 1.0L*dp[i][j] + sqrtl(H[i] * H[i] + W[i] * W[i]));
		}
	}
	long double sum1 = 0.0L;
	for (int i = 0; i < N; i++) { P -= 2.0L*(H[i] + W[i]); sum1 += 2.0L*(H[i] + W[i]); }
	P /= 2;
	long double ret = 0.0L;
	for (int j = 0; j <= N * 250; j++) {
		if (dp[N][j] <= -1e8 || 1.0L*j >= P + 1e-7) continue;
		ret = max(ret, 1.0L*min(P, dp[N][j]));
	}
	return ret*2.0L + sum1;
}
 
int main() {
	cin >> T;
	for (int i = 0; i < T; i++) {
		cin >> N >> P;
		for (int j = 0; j < N; j++) cin >> H[j] >> W[j];
 
		printf("Case #%d: %.12Lf\n", i + 1, solve());
	}
	return 0;
}

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4
1 7
1 1
2 920
50 120
50 120
1 32
7 4
3 240
10 20
20 30
30 10