#include <bits/stdc++.h>
using namespace std;
using ld = long double;
using ull = unsigned long long;
/*
#pragma comment(linker, "/STACK:256000000")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("-O3")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
*/
template <class T> inline T gcd(T a , T b) { return !a ? b : gcd(b % a , a); }
template <class T> inline T lcm(T a , T b) { return (a * b) / gcd(a , b) ; }
mt19937 rnd(time(0));
#define all(x) x.begin(), x.end()
#define debug(x) { cerr << #x << " = " << x << endl; }
void solve() {
int n;
cin >> n;
vector<pair<long long, int>> a(n);
for (int i = 0; i < n; i++) {
cin >> a[i].first >> a[i].second;
}
sort(all(a));
long long ans = 0ll, sum = 0ll;
for (int i = 0; i < n; i++) {
sum += a[i].second;
ans = max(ans, sum - a[i].first + a[0].first);
}
cout << ans << '\n';
return;
}
signed main() {
ios_base :: sync_with_stdio(0);
cin.tie(0) , cout.tie(0);
int t = 1;
while (t-- > 0) {
solve();
}
return 0;
}
