#include <bits/stdc++.h>
using namespace std;
#define int int64_t
#define f0(i, n) for(int32_t i = 0; i < (n); i++)
#define f1(i, n) for(int32_t i = 1; i <= (n); i++)
#define inp(x) int x; cin >> x
#define inp2(a, b) int a, b; cin >> a >> b
#define ff first
#define ss second
void solve1() {
inp(n);
int A[n], B[n];
pair<int, int> ab[n];
f0(i,n) {
cin >> ab[i].ff >> ab[i].ss;
}
sort(ab, ab+n);
f0(i, n) A[i] = ab[i].ff, B[i] = ab[i].ss;
int pref[n+1] = {0};
f1(i, n) pref[i] = pref[i-1] + B[i-1];
int indi[n];
f0(i,n) {
indi[i] = pref[i+1] - A[i];
}
pair<int, int> sufmx[n+1];
sufmx[n] = {0, -1};
for(int i = n-1; i >= 0; i--) {
if(indi[i] > sufmx[i+1].ff) {
sufmx[i] = {indi[i], i};
} else {
sufmx[i] = sufmx[i+1];
}
}
int ans = 0;
f0(i, n) {
int j = sufmx[i].ss;
ans = max(ans, pref[j+1] - pref[i] - A[j] + A[i]);
}
cout << ans << endl;
}
void solve2() {
inp(n);
int A[n], B[n];
pair<int, int> ab[n];
f0(i,n) {
cin >> ab[i].ff >> ab[i].ss;
}
sort(ab, ab+n);
f0(i, n) A[i] = ab[i].ff, B[i] = ab[i].ss;
int pref[n+1] = {0};
f1(i, n) pref[i] = pref[i-1] + B[i-1];
int indi[n];
f0(i,n) {
indi[i] = pref[i+1] - A[i];
}
pair<int, int> sufmx[n+1];
sufmx[n] = {-1e18, -1};
for(int i = n-1; i >= 0; i--) {
if(indi[i] > sufmx[i+1].ff) {
sufmx[i] = {indi[i], i};
} else {
sufmx[i] = sufmx[i+1];
}
}
int ans = 0;
f0(i, n) {
int j = sufmx[i].ss;
ans = max(ans, int64_t(pref[j+1] - pref[i] - A[j] + A[i]));
// cout << j;
}
cout << ans << endl;
}
int32_t main() {
#if __has_include("LOCAL.hh")
#include "LOCAL.hh"
#endif
#ifdef LOCAL
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#else
ios_base::sync_with_stdio(0);
cin.tie(0);
#endif
solve2();
return 0;
}
