//https://oj.uz/problem/view/LMIO19_bulves
#include<iostream>
#include<vector>
#include<set>
#include<map>
#include<iomanip>
#include <cassert>
#include<algorithm>
#include<queue>
#include <array>
#include <bitset>
using namespace std;
#define int long long
#define pii pair<int,int>
int INF = 1e18;
int a[500001];
int n;
void ez(){
int cur = 0;
int ans = 0;
for(int i = 1; i <= n; ++i){
cur += a[i];
ans += abs(cur);
}
cout << ans << "\n";
}
void onedp(){
}
int32_t main(){
cin.tie(0)->sync_with_stdio(0);
cin >> n;
int sumA = 0;
for(int i = 1; i <= n; ++i){
int x, y; cin >> x >> y;
a[i] = x - y;
}
if(sumA == 0){
ez();
} else{
onedp();
}
}
