Tram.cpp

// https://codeforces.com/problemset/problem/116/A
#include <bits/stdc++.h>

#define fi          first
#define se          second
#define pb          push_back
#define mp          make_pair
#define ll          long long
#define pll         pair<long, long>
#define vll         vector<long long>
#define inf         1e18
#define range(a,b)  substr(a,b-a+1)
#define FIO         ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)

using namespace std;

int main()
{
    FIO;

    #ifndef ONLINE_JUDGE
        freopen("input.txt", "r", stdin);
        freopen("output.txt", "w", stdout);
    #endif

    ll n, a, b, t;
    vll arr;
    cin >> n;
    t = n;
    while (t--) {
        cin >> a >> b;
        arr.pb(b - a);
    }
    ll ans = arr[0];
    for (int i = 1; i < n; i++) {
        arr[i] += arr[i - 1];
        if (ans < arr[i])
            ans = arr[i];
    }
    cout << ans;
    return 0;
}