//Mert Akarca <3
#include <bits/stdc++.h>
#define int long long
using namespace std;
int n,tempb,tempd,toplam,mn,mx,ans;
vector <int> boyut;
vector <int> deger;
int solve(int t, int maks, int mini, int cindex)
{
if(cindex == n) if(maks != LLONG_MIN && mini != LLONG_MAX) return t-(abs(maks - mini)); else return 0;
ans = max(solve(t,maks,mini,cindex+1), solve(t + deger[cindex],max(maks,boyut[cindex]),min(boyut[cindex],mini),cindex+1));
return ans;
}
int32_t main()
{
ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
cin>>n;
for(int j = 0; j<n; ++j)
{
cin>>tempb>>tempd;
boyut.push_back(tempb);
deger.push_back(tempd);
}
cout<<solve(0,LLONG_MIN,LLONG_MAX,0);
}
