//Mitesh Agrawal
#include <bits/stdc++.h>
using namespace std;
 
#define ii pair<ll,ll>
#define dd pair<double,ll>
#define ll long long
 
ll n,k;
ii cake[1005];
dd dp[1005][1005];
 
//ans, last index
dd f(ll idx, ll req){
	ll i,j;
	dd &ans = dp[idx][req];
	dd ans1, ans2;
	if(ans != dd(-1,-1)) return ans;
	if(req == 0) return ans = ii(0,-1);
	if(idx + 1 == req){
		ans.first = M_PI * cake[idx].first * cake[idx].first;
		for(i = 0; i <= idx; i++)
			ans.first += M_PI * 2.0 * cake[i].first * cake[i].second;
		ans.second = idx;
		return ans;
	}
	ans1 = f(idx - 1, req);
	ans2 = f(idx - 1, req - 1);
	if(ans2.second > -1)
		ans2.first -= M_PI * cake[ans2.second].first * cake[ans2.second].first;
	ans2.first += M_PI * cake[idx].first * cake[idx].first;
	ans2.first += M_PI * 2.0 * cake[idx].first * cake[idx].second;
	ans2.second = idx;
	return ans = max(ans1, ans2);
}
 
int main(){
	ll i,j,test,t;
	scanf("%lld",&t);
	for(test = 1; test <= t; test++){
		scanf("%lld %lld",&n,&k);
		for(i = 0; i < n; i++)
			scanf("%lld %lld",&cake[i].first, &cake[i].second);
		sort(cake, cake+n);
		for(i = 0; i <= n; i++)
			for(j = 0; j <= k; j++)
				dp[i][j] = dd(-1, -1);
		printf("Case #%lld: %0.12lf\n",test, f(n-1, k).first);
	}
    return 0;
}

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4
2 1
100 20
200 10
2 2
100 20
200 10
3 2
100 10
100 10
100 10
4 2
9 3
7 1
10 1
8 4