#include <bits/stdc++.h>   using namespace std;   int main() {     int n;     long long int sum = 0;     cin >> n;     int a, b;     int max = INT_MIN;     for (int i = 0; i < n; i++) {       cin >> a >> b;       sum = sum - a + b;       if (max < sum) max = sum;     }     cout << max;     return 0;   }   