rt

#include<bits/stdc++.h>
using namespace std;
int sum[300005],visl[300005],visr[300005],n,l=30000005,r,s,t,ans,cnt;
int main() {
	cin>>n;
	for(int i=1; i<=n; i++) {
		cin>>l>>r;
		visl[l]=1;
		visr[r]=1;
		s=min(l,s);
		t=max(t,r);
		sum[l]++;
		sum[r+1]--;
	}
	l=0;
	r=0;
	for(int i=s; i<=t; i++) {
		sum[i]+=sum[i-1];
		if(cnt==0&&sum[i]>0&&!(visl[i]&&visr[i])&&!visr[i]) {
			cnt=sum[i];
			l=i;
			continue;
		}
		if(visl[i]||visr[i]) {
			if((visl[i]&&visr[i])||visl[i])
			ans=max(ans,(i-1-l)*cnt);
			else
			ans=max(ans,(i-l)*cnt);
//			cout<<i<<" "<<cnt<<" "<<i-l<<endl;
			cnt=0;
			if(visl[i]&&!visr[i]) {
				l=i;
				cnt=sum[i];
			}
		}
	}
	cout<<ans;
}