#include <bits/stdc++.h>
using namespace std;
const int maxn = 5e5 + 10;
const long long inf = 1e16;
long long pre[maxn];
int a[maxn], b[maxn];
struct node {
long long val, lazy;
int index;
node () { val = lazy = index = 0; }
node (long long val) : val(val) { lazy = index = 0; }
void add(long long x) {
val += x;
lazy += x;
}
};
struct segtree {
vector <node> t;
int size;
long long useless;
function <long long(long long, long long)> func;
void merge(node &cur, node l, node r) {
cur.val = func(l.val, r.val);
if(cur.val == r.val) cur.index = r.index;
if(cur.val == l.val) cur.index = l.index;
}
void pushdown(int c) {
int l = c << 1;
int r = l + 1;
t[l].add(t[c].lazy);
t[r].add(t[c].lazy);
t[c].lazy = 0;
}
void build(int c, int b, int e) {
t[c].val = 0;
t[c].lazy = 0;
if(b == e) {
t[c].index = b;
return ;
}
int m = (b + e) >> 1;
int l = c << 1;
int r = l + 1;
build(l, b, m);
build(r, m + 1, e);
merge(t[c], t[l], t[r]);
}
segtree(int size, long long useless, function <long long(long long, long long)> func) : size(size), useless(useless), func(func) {
t.resize(4 * size + 1);
build(1, 1, size);
}
void update(int x, int y, long long val, int c, int b, int e) {
if(x <= b && e <= y) {
t[c].add(val);
return ;
}
if(y < b || e < x) return ;
pushdown(c);
int m = (b + e) >> 1;
int l = c << 1;
int r = l + 1;
update(x, y, val, l, b, m);
update(x, y, val, r, m + 1, e);
merge(t[c], t[l], t[r]);
}
node query(int x, int y, int c, int b, int e) {
if(x <= b && e <= y) return t[c];
if(y < b || e < x) return node(useless);
pushdown(c);
int m = (b + e) >> 1;
int l = c << 1;
int r = l + 1;
node ans;
merge(ans, query(x, y, l, b, m), query(x, y, r, m + 1, e));
return ans;
}
void update(int x, int y, long long val) {
update(x, y, val, 1, 1, size);
}
pair <long long, int> query(int x, int y) {
node ans = query(x, y, 1, 1, size);
return make_pair(ans.val, ans.index);
}
};
int main() {
int n;
cin >> n;
for(int i = 1; i <= n; i++) {
cin >> a[i] >> b[i];
pre[i] = pre[i - 1] + a[i] - b[i];
}
segtree profit (n, -inf, [] (long long i, long long j) { return i < j ? j : i; } );
int cnt = 0;
for(int i = n; i >= 1; i--) {
if(pre[i] > 0) ++cnt;
else --cnt;
profit.update(i, i, cnt);
}
while(pre[n] > 0) {
int id = profit.query(1, n).second;
long long minVal = pre[n];
for(int i = id; i <= n; i++) {
if(pre[i] > 0) minVal = min(minVal, pre[i]);
}
for(int i = id; i <= n; i++) {
pre[i] -= minVal;
if(pre[i] == 0) {
profit.update(1, i, -2);
}
}
}
long long ans = 0;
for(int i = 1; i <= n; i++) ans += abs(pre[i]);
cout << ans << endl;
}
