#include <bits/stdc++.h>
using namespace std;
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
int n;
cin >> n;
vector<int>a(n + 1), b(n + 1);
vector<long long>p(n + 1);
for(int i = 1;i <= n;++i){
cin >> a[i] >> b[i];
p[i] = p[i - 1] + (a[i] - b[i]);
}
vector<vector<long long>>dp(2, vector<long long>(p[n] + 1));
for(int i = 1;i < n;++i){
for(int j = 0;j <= p[n];++j){
dp[1][j] = dp[0][j] + abs(p[i] - j);
if(j - 1 >= 0)dp[1][j] = min(dp[1][j], dp[1][j - 1]);
}
// cout << "dp[" << i << "] = ";
// for(int j = 0;j <= p[n];++j){
// cout << dp[1][j] << " ";
// }
// cout << '\n';
for(int j = 0;j <= p[n];++j){
dp[0][j] = dp[1][j];
dp[1][j] = 0;
}
}
cout << dp[0][p[n]];
}
