#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <cstdlib>
using namespace std;

const int MAXN = 200100;
const int SIZ = 1<<18;

int sum[SIZ * 2 + 100], minBelow[SIZ * 2 + 100];

int loc[MAXN][2];
int n;

struct eventtype {
	int x;
	int ylow;
	int yhigh;
	int typ;
	eventtype() {}
	eventtype(int nx, int nylow, int nyhigh, int ntyp) {
		x = nx; ylow = nylow; yhigh = nyhigh; typ = ntyp;
	}
	bool operator < (const eventtype &o) const {
		return x < o.x;
	}
};

int rect[MAXN][4];
int rt;

eventtype event[MAXN * 2];
int et;

pair<int,int> ylist[MAXN * 2];
int yt;

void reCalc(int p) {
	if(p < SIZ) {
		minBelow[p] = min(minBelow[p * 2], minBelow[p * 2 + 1]);
	}
	else {
		minBelow[p] = 0;
	}
	minBelow[p] += sum[p];
}

void add(int p, int l, int r, int lGoal, int rGoal, int v) {
//if(p < 1 || p >= SIZ * 2) {puts("FUBAR"); exit(0);}
	if(l == lGoal && r == rGoal) {
		sum[p] += v;
	}
	else {
		int mid = (l + r) / 2;
		if(rGoal <= mid) add(p * 2, l, mid, lGoal, rGoal, v);
		else if(mid < lGoal) add(p * 2 + 1, mid + 1, r, lGoal, rGoal, v);
		else {
			add(p * 2, l, mid, lGoal, mid, v);
			add(p * 2 + 1, mid + 1, r, mid + 1, rGoal, v);
		}
	}
	reCalc(p);
}

int canEscape(int d) {
//printf("Checking %d\n", d); fflush(stdout);
	yt = 0;
	rt = 0;
	for(int i = 0; i < n; ++i) {
		rect[rt][0] = max(-d, loc[i][0] - d);
		rect[rt][1] = max(-d, loc[i][1] - d);
		rect[rt][2] = min(d, loc[i][0] + d) + 1;
		rect[rt][3] = min(d, loc[i][1] + d) + 1;
//printf("%d %d\n", loc[i][0], loc[i][1]);
		if(rect[rt][0] < rect[rt][2] && rect[rt][1] < rect[rt][3]) {
			ylist[yt++] = make_pair(rect[rt][1], rt * 4 + 1);
			ylist[yt++] = make_pair(rect[rt][3], rt * 4 + 3);
			++rt;
		}
	}
	ylist[yt++] = make_pair(-d, -1);
	ylist[yt++] = make_pair(d + 1, -1);
	sort(ylist, ylist + yt);
	int ytot = 0;
	for(int i = 0; i < yt; ++i) {
		if(i > 0 && ylist[i].first != ylist[i - 1].first) {
			ytot++;
		}
		if(ylist[i].second != -1) {
			rect[ylist[i].second / 4][ylist[i].second % 4] = ytot;
		}
	}
//for(int i = 0; i < rt; ++i) printf("(%d %d) - (%d %d)\n", rect[i][0], rect[i][1], rect[i][2], rect[i][3]); 

	et = 0;
	for(int i = 0; i < rt; ++i) {
		event[et++] = eventtype(rect[i][0], rect[i][1], rect[i][3] - 1, 1);	
		event[et++] = eventtype(rect[i][2], rect[i][1], rect[i][3] - 1, -1);
	}

	sort(event, event + et);
	if(et == 0) {
		return 1;
	}
	
	int i = 0;
	memset(sum, 0, sizeof(sum));
	memset(minBelow, 0, sizeof(minBelow));
	add(1, 0, SIZ - 1, ytot, SIZ - 1, 1);
//printf("%d %d\n", ytot, SIZ - 1);
	if(event[0].x != -d) {
		return 1;
	}	
	while(1) {
		int x = event[i].x;
		if(x == d + 1) {
//puts("COVERED");
			return 0;
		}
		while(i < et && event[i].x == x) {
//printf("%d:   %d %d %d\n", x, event[i].ylow, event[i].yhigh, event[i].typ); fflush(stdout);
			add(1, 0, SIZ - 1, event[i].ylow, event[i].yhigh, event[i].typ);
//printf("%d\n", minBelow[1]); fflush(stdout);
			++i;
		}
		if(minBelow[1] == 0) {
			return 1;
		}
	}
//if(n != 4) {puts("FUBAR"); exit(0);}
}

int main() {
	int ct = 0;
	scanf("%d", &n);
	while(n != -1) {
		for(int i = 0; i < n; ++i) {
			scanf("%d%d", &loc[i][0], &loc[i][1]);
		}
//printf(":::%d\n", canEscape(1)); return 0;
		++ct;
		printf("Case %d: ", ct);
		if(canEscape(1<<30)) {
			puts("never");
		}
		else {
			int ans = 0;
			int del = 1<<29;
			while(del) {
				if(canEscape(ans + del)) {
					ans += del;
				}
				del /= 2;
			}
			printf("%d\n", ans + 1);
		}
		scanf("%d", &n);
	}
	return 0;
}