Pachete

#include <bits/stdc++.h>
#define int long long
#define pi pair < int , int >
#define x first
#define y second
// http://campion.edu.ro/arhiva/index.php?page=problem&action=view&id=513

using namespace std;

ifstream fin("pachete.in");
ofstream fout("pachete.out");

int32_t main() {
    int N;
    fin >> N;
    vector < pi > a(N);
    for(int i = 0; i < N; ++i)
        fin >> a[i].x >> a[i].y;
    vector < int > dp(N + 1);
    for(int i = N - 1; i >= 0; --i)
        dp[i] = a[i].y + max(0LL, dp[i + 1] - a[i].x);
    fout << dp[0];
}