一道站外题，一直RE

#include<bits/stdc++.h>
using namespace std;
int n,pre[30005],a,b,ans=0;
int main(){
	freopen("sx.in", "r", stdin);
	freopen("sx.out", "w", stdo	
	scanf("%d",&n);
	for(int i=1;i<=n;i++){
		scanf("%d%d",&a,&b);
		pre[a]++;
		pre[b+1]--;
	}
	for(int i=1;i<=3000000;i++){
		pre[i]+=pre[i-1];
		ans=max(ans,pre[i]);
	}
	cout<<ans;
	return 0;
}