题意：
思路：
#include<cstdio>
#include<iostream>
#include<cstring>
#include<cmath>
#include<stdlib.h>
#include<vector>
#include<queue>
#include<stack>
#include<algorithm>
using namespace std;
struct Work
{
__int64 c,d;
};
Work work[100000+10];
int cmp(Work a,Work b)
{
if(a.d==b.d)
{
return a.c<b.c;
}
return a.d<b.d;
}
int main()
{
__int64 time ,ans;
int cas=1;
int t,n;
int i,j,k;
scanf("%d",&t);
while(t--)
{
ans=0;time=0;
scanf("%d",&n);
for(i=0;i<n;i++)
{
scanf("%I64d%I64d",&work[i].c,&work[i].d);
}
sort(work,work+n,cmp);
for(i=0;i<n;i++)
{
time+=work[i].c;
if(time>work[i].d&&ans<time-work[i].d)
{
ans=time-work[i].d;
}
}
printf("Case %d: %I64d
",cas++,ans);
}
return 0;
}