#include<bits/stdc++.h>
# define int long long
# define rep(i, j, k) for (int i = j; i <= k; ++i)
# define dis(i, j) sqrt((x[i] - x[j]) * (x[i] - x[j]) + (y[i] - y[j]) * (y[i] - y[j]))
using namespace std;

int n, x[1000005], y[1000005], dx[1000005], dy[1000005], st[1000005];
int qex[10] = {0, 1, 1, 1, -4, 3, 5, 7}, qey[10] = {1, 0, 1, -2, 9, 4, -3, 2};
bool b = true;
long double d[105][105], anx[1000005];
double ddl[1000005][21];
void solvebf()
{
    long double ans = 10000000000000000LL;
    rep(i, 1, n) rep(j, i + 1, n) d[i][j] = sqrt((x[i] - x[j]) * (x[i] - x[j]) + (y[i] - y[j]) * (y[i] - y[j]));
    rep(i, 1, n) rep(j, i + 1, n) rep(k, j + 1, n) ans = min(ans, d[i][j] + d[i][k] + d[j][k]);
    cout << fixed << setprecision(15) << ans << '\n';
}
bool cmp(int a, int b){return x[a] < x[b];}
void solveeasy()
{
    rep(i, 1, n) st[i] = i;
    sort(st + 1, st + n + 1, cmp);
    int ans = 100000000000LL;
    rep(i, 1, n - 2) ans = min(ans, 2 * (x[st[i + 2]] - x[st[i]]));
    cout << ans << '\n';
}
bool cmp1(int a, int b){return anx[a] < anx[b];}
void solvediff()
{
    double ans = 1000000000000000LL;
    rep(i, 1, n) x[i] += 1000000001, y[i] += 1000000001;
    rep(i, 1, n) dx[i] = 3 * x[i] - 4 * y[i] + 10000000001LL, dy[i] = 4 * x[i] + 3 * y[i] + 10000000001LL, anx[i] = (long double) (1.0) * dx[i] + dy[i], st[i] = i;
    sort(st + 1, st + n + 1, cmp);
    rep(i, 1, n) rep(k, 1, 20) if (i + k <= n) ddl[i][k] = dis(st[i], st[i + k]);
    rep(i, 1, n) rep(j, i + 1, min(i + 20, n)) rep(k, j + 1, min(i + 20, n)) ans = min(ans, ddl[i][j - i] + ddl[i][k - i] + ddl[j][k - j]);

    rep(i, 1, n) dx[i] = 1 * x[i] + 3 * y[i] + 10000000001LL, dy[i] = 3 * x[i] - 1 * y[i] + 10000000001LL, anx[i] = (long double) (1.0) * dx[i] + dy[i];
    sort(st + 1, st + n + 1, cmp1);
    rep(i, 1, n) rep(k, 1, 20) if (i + k <= n) ddl[i][k] = dis(st[i], st[i + k]);
    rep(i, 1, n) rep(j, i + 1, min(i + 20, n)) rep(k, j + 1, min(i + 20, n)) ans = min(ans, ddl[i][j - i] + ddl[i][k - i] + ddl[j][k - j]);

    rep(i, 1, n) dx[i] = 3 * x[i] + 1 * y[i] + 10000000001LL, dy[i] = 1 * x[i] - 3 * y[i] + 10000000001LL, anx[i] = (long double) (1.0) * dx[i] * dy[i];
    sort(st + 1, st + n + 1, cmp1);
    rep(i, 1, n) rep(k, 1, 20) if (i + k <= n) ddl[i][k] = dis(st[i], st[i + k]);
    rep(i, 1, n) rep(j, i + 1, min(i + 20, n)) rep(k, j + 1, min(i + 20, n)) ans = min(ans, ddl[i][j - i] + ddl[i][k - i] + ddl[j][k - j]);

    cout << fixed << setprecision(15) << ans << '\n';
}
signed main()
{
//    freopen("triangle.in", "r", stdin);
//    freopen("triangle.out", "w", stdout);
    ios::sync_with_stdio(false); cin.tie(0), cout.tie(0);
    int T; cin >> T; rep(tt, 1, T)
    {
    	cout << "Case #" << tt << ": ";
    cin >> n;
    rep(i, 1, n) cin >> x[i] >> y[i], b &= (!y[i]);
    if (n <= 100) solvebf();
    else if (b) solveeasy();
    else solvediff();
	}
    return 0;
}