#include<stdio.h>#include<algorithm>typedef struct event{int x;int t;} event;event e[100000];int cmp(const void *a, const void *b){event *e1, *e2;e1 = (event *)a;e2 = (event *)b;if(e1->x != e2->x) return e1->x - e2->x;else return e1->t - e2->t;}int check(int t, int n, int m){int last_b,last_e,begin,end,count,i;last_b = e[0].x - (e[0].t-t);last_e = e[0].x + (e[0].t-t);count=1;for(i=1; i<n; i++){begin= e[i].x - (e[i].t-t);end= e[i].x + (e[i].t-t);if(last_e < begin){count++;if(count > m) return 0;last_b = begin;last_e = end;}else {if(last_b <= begin) last_b = begin;if(end <= last_e) last_e = end; }}return 1;}int main(){int cases, n, m, i, j;int t_max, t_min, mid, ans;scanf("%d", &cases);for(i=0; i<cases; i++){scanf("%d%d", &n, &m);t_max=1000000;t_min=-2000000;for(j=0; j<n; j++){scanf("%d%d", &e[j].t, &e[j].x);if(e[j].t < t_max) t_max=e[j].t;}qsort(e, n, sizeof(event), cmp);while(t_min <= t_max){mid=(t_min + t_max) >> 1;if(check(mid, n, m)){ans = mid;//继续往上找 t_min=mid+1;}else t_max=mid-1;}printf("Case %d: %dn", i+1, ans);}return 0;}
