为什么会错？有大佬帮一下吗？

#include<bits/stdc++.h>
using namespace std;
int n,i;
long long l[5050],r[5050],s=0,x=0,y,z,b1,b2;
int main(){
	cin>>n;
	for(i=1;i<=n;i++){
		cin>>l[i]>>r[i];
	}
	if(l[i+1]<=r[i]){
		s=(r[i+1]-l[i]);
	}
	else{
		x=(l[i+1]-r[i]);
	}
	for(i=1;i<n;i++){
		if(l[i+1]<=r[i]){
			y=(r[i+1]-l[i]);
			b1=max(s,y);
		}
		else{
			z=(l[i+1]-r[i]);
			b2=max(x,z);
		}
	}
	cout<<b1<<" "<<b2;
	return 0;
}