WA球跳

#include<cstdio>
#include<cstring>
#include<vector>
#include<algorithm>
#define PII pair<int,int>
#define fir first
#define sec second
using namespace std;
namespace Main{
	const int N=1e5+7;
	int T,n,res;
	PII s[N];
	inline void main(){
		scanf("%d",&T);
		while(T--){
			scanf("%d",&n);
			for(int i=1;i<=n;i++){
				scanf("%d%d",&s[i].fir,&s[i].sec);
			}
			sort(s+1,s+n+1);
			s[0]=s[n+1]={-1,-1};
			int cnt=0;
			for(int i=1;i<=n+1;i++){
				if(s[i-1].fir!=s[i].fir){
					res+=cnt;
					bool flag=0;
					int j=i;
					while(s[j].sec<s[i-1].fir+cnt){
						if(j>=n){
							flag=1;
							break;
						}
						++j;
					}
					i=j;
					if(flag){
						break;
					}
					cnt=0;
				}
				cnt+=(bool)(cnt<=(s[i].sec-s[i].fir));
			}
			printf("%d\n",res);
			res=0;
		}
		return ;
	}
}
signed main(){
	Main::main();
	return 0;
}