#include <bits/stdc++.h> using namespace std; #define int long long #define all(x) x.begin(), x.end() #define inf (int)3e18 #define ff first #define ss second using vi = vector<int>; using vii = vector<pair<int, int>>; using vvi = vector<vector<int>>; using pii = pair<int, int>; mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count()); const int MAX = 5e5 + 5; array<int, 3> dp[MAX]; int a[MAX], b[MAX]; void solve() { int n; cin >> n; for (int i = 1; i <= n; i++) cin >> a[i] >> b[i]; dp[1][0] = b[1]; dp[1][1] = a[1]; dp[1][2] = a[1]; for (int i = 2; i <= n; i++) { // If we dont take -> s // If we take -> sn int S = dp[i - 1][0] - dp[i - 1][1] + dp[i - 1][2]; int Sn = dp[i - 1][0] + b[i] - max(dp[i - 1][1], a[i]) + min(dp[i - 1][2], a[i]); if (Sn > S) { dp[i][0] = dp[i - 1][0] + b[i]; dp[i][1] = max(dp[i - 1][1], a[i]); dp[i][2] = min(dp[i - 1][2], a[i]); } else { dp[i] = dp[i - 1]; } } // for (int i = 1; i <= n; i++) // { // cout << dp[i][0] << ' ' << dp[i][1] << ' ' << dp[i][2] << '\n'; // } cout << dp[n][0] - dp[n][1] + dp[n][2]; } signed main() { ios::sync_with_stdio(0); cin.tie(0); int tt = 1; // cin >> tt; while (tt--) solve(); }