#include <bits/stdc++.h>
using namespace std;
#define mod 1000000007
#define maxn 200005
#define f first
#define s second
#define ll long long
#define pb(x) push_back(x)
void solve(){
int n;
cin >> n;
pair<long long, long long> p[n];
for(int i=0; i<n; i++){
cin >> p[i].f >> p[i].s;
}
sort(p, p+n);
long long sum=p[0].s, ans=p[0].s;
for(int i=1; i<n; i++){
if(sum+p[i].s-p[i].f+p[i-1].f<0){
sum=p[i].f;
}else{
sum+=p[i].s-p[i].f+p[i-1].f;
}
ans=max(ans, sum);
}
cout << ans;
}
int main(){
cin.tie(nullptr)->sync_with_stdio(0);
int t=1;
//cin >> t;
while(t--){
solve();
}
return 0;
}
