1 #include<algorithm>
 2 #include<iostream>
 3 #include<cstdlib>
 4 #include<cstring>
 5 #include<cstdio>
 6 #include<vector>
 7 #include<map>
 8 using std::max;
 9 using std::cin;
10 using std::cout;
11 using std::endl;
12 using std::fabs;
13 using std::sort;
14 using std::pair;
15 using std::vector;
16 #define pb(e) push_back(e)
17 #define sz(c) (int)(c).size()
18 #define mp(a, b) make_pair(a, b)
19 #define all(c) (c).begin(), (c).end()
20 #define iter(c) decltype((c).begin())
21 #define cls(arr,val) memset(arr,val,sizeof(arr))
22 #define cpresent(c, e) (find(all(c), (e)) != (c).end())
23 #define rep(i, n) for (int i = 0; i < (int)(n); i++)
24 #define tr(c, i) for (iter(c) i = (c).begin(); i != (c).end(); ++i)
25 const int N = 10010;
26 typedef unsigned long long ull;
27 struct Node {
28     int t, x;
29     bool operator<(const Node &b) const {
30         return t < b.t;
31     }
32 }rec[N];
33 int main() {
34 #ifdef LOCAL
35     freopen("in.txt", "r", stdin);
36     freopen("out.txt", "w+", stdout);
37 #endif
38     int t, n, k = 1;
39     scanf("%d", &t);
40     while (t--) {
41         double ans = 0.0;
42         scanf("%d", &n);
43         rep(i, n) scanf("%d %d", &rec[i].t, &rec[i].x);
44         sort(rec, rec + n);
45         for (int i = 1; i < n; i++) {
46             ans = max(ans, fabs((double)rec[i].x - rec[i - 1].x) / (rec[i].t - rec[i - 1].t));
47         }
48         printf("Case #%d: %.2lf\n", k++, ans);
49     }
50     return 0;
51 }