#include <bits/stdc++.h> #define mod 1000000007 #define pb push_back #define mid(l, r) ((l)+(r))/2 #define len(a) (a).length() #define sz(a) (a).size() #define xx first #define yy second #define inf int(2e9) #define ff(i, a, b) for(int (i) = (a); (i) <= (b); ++(i)) #define fb(i, a, b) for(int (i) = (a); (i) >= (b); --(i)) #define maxn 500005 using namespace std; typedef long long ll; typedef pair<ll,ll> pii; template<class T> void print(const T niz[], const int siz) { for(int i=0;i<siz;i++) cout << niz[i] << " "; cout << endl; } int n; pii niz[maxn]; ll sol = -1e9; ll mini; bool cmp(pii a, pii b){ return a.yy < b.yy; } int main() { ios_base::sync_with_stdio(false); cin >> n; ff(i,1,n){ int a, b; cin >> a >> b; niz[i] = {b,a}; } sort(niz + 1, niz + n + 1,cmp); mini = -niz[1].yy; ll sum = 0; ff(i,1,n){ sum += niz[i].xx; sol = max(sol, sum - mini - niz[i].yy); mini = min(mini, sum - niz[i+1].yy); } cout << sol << endl; return 0; }