#include<bits/stdc++.h>
#define int long long
#define ld long double
#define pii pair<int, int>
#define vi vector<int>
#define vvi vector<vi>
#define pb push_back
#define fi first
#define se second
#define TII tuple<int, int, int>
#define MT make_tuple
#define mp make_pair
#define ts to_string
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
#define MIN(x) *min_element(all(x))
#define MAX(x) *max_element(all(x))
#define lb lower_bound
#define ub upper_bound
#pragma GCC optimize("O3", "unroll-loops")
using namespace std;
const int INF = 1e15, ADD = 3e4 + 1, MX = 6e4 + 5, N = 3'005;
int dp[2][MX];
void cmin(int &a, int b) { a = min(a, b); }
int32_t main() {
ios_base::sync_with_stdio(false); cin.tie(NULL);
int n; cin >> n;
for(int i = 0; i < 2; i++) for(int j = 0; j < MX; j++) dp[i][j] = INF;
dp[0][ADD] = 0;
// dp_idx = real_idx + ADD
// real_idx = dp_idx - ADD
for(int i = 1; i <= n; i++) {
int a, b; cin >> a >> b;
int cur = (i & 1), prv = (cur ^ 1);
for(int j = -ADD; j <= ADD; j++) dp[cur][j + ADD] = INF;
if(a < b) {
for(int j = -ADD; j <= ADD; j++) {
if(j + (b - a) <= ADD) cmin(dp[cur][j + ADD], dp[prv][j + (b - a) + ADD] + abs(j + (b - a)));
}
} else {
for(int j = -ADD; j <= ADD; j++) {
for(int k = 0; k <= a - b; k++) {
if(j - k >= -ADD) cmin(dp[cur][j + ADD], dp[prv][j - k + ADD] + abs(j - k));
}
}
}
// cout << "________" << endl;
// for(int j = -ADD; j <= ADD; j++) {
// if(abs(j) <= 3) cout << j << " : " << dp[cur][j + ADD] << endl;
// }
}
cout << dp[n & 1][ADD] << '\n';
return 0;
}
