/* -*- coding: utf-8 -*-
 *
 * 999.cc:  No.999 てん vs. ほむ - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 100000;
const long long LINF = 1LL << 62;

/* typedef */

typedef long long ll;

/* global variables */

ll ass[MAX_N + 1], bss[MAX_N + 1];

/* subroutines */

/* main */

int main() {
  int n;
  scanf("%d", &n);

  for (int i = 0; i < n; i++) {
    int a, b;
    scanf("%d%d", &a, &b);
    ass[i + 1] = ass[i] + a;
    bss[i + 1] = bss[i] + b;
  }

  ll maxd = -LINF;
  for (int i = 0; i <= n; i++) {
    ll h = ass[i] + (bss[n] - bss[i]);
    ll t = bss[i] + (ass[n] - ass[i]);
    ll d = h - t;
    if (maxd < d) maxd = d;
  }

  printf("%lld\n", maxd);
  return 0;
}