#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")
#include <bits/stdc++.h>
#define ll long long
#define vi vector<int>
#define vvi vector<vi>
#define pb push_back
#define FOR(i, a, b) for(int i = a; i <= b; ++i)
#define FORR(i, a, b) for(int i = a; i >= b; --i)
#define pii pair<int, int>
#define ff first
#define ss second
#define pll pair<ll, ll>
#define vpi vector<pii>
#define vvpi vector<vpi>
#define vpl vector<pll>
#define vvpl vector<vpl>
#define vl vector<ll>
#define vvl vector<vl>
//#define x first
//#define y second
using namespace std;
const int N = 1e6 + 9, LGV = 33, LGN = 21, Mod = 1e9 + 7;
const int Inf = 0x3f3f3f3f;
//const ll Inf = LLONG_MAX / 2;
const bool test_case = false;
//ifstream fin("input.txt");
//ofstream fout("output.txt");
//#define cin fin
//#define cout fout
int n, a[N], b[N];
ll sa[N], sb[N];
void solve()
{
cin >> n;
FOR(i, 1, n)cin >> a[i] >> b[i];
FOR(i, 1, n)sa[i] = sa[i - 1] + a[i];
FOR(i, 1, n)sb[i] = sb[i - 1] + b[i];
ll ans = 0;
FOR(i, 1, n)
ans += abs(sa[i] - sb[i]);
cout << ans << '\n';
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0), cout.tie(0);
int t = 1;
if(test_case)cin >> t;
while(t --)solve();
return 0;
}
