#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < (n);i++)
#define sz(x) int(x.size())
typedef long long ll;
typedef pair<int,int> P;
constexpr ll INF = (1LL << 55);
int main(){
  int n;
  cin >> n;
  vector<ll> a(n), b(n);
  rep(i,n) cin >> a[i] >> b[i];
  vector<vector<ll>> dp(n+1, vector<ll>(2, INF));
  dp[0][0] = 0;
  dp[0][1] = 0;

  for (int i = 0; i < n; i++) {
    for (int j = 0; j < 2; j++) {
      dp[i+1][j] = min(dp[i+1][j], dp[i][j] + (j ? b[i] : a[i]));
      dp[i+1][j] = min(dp[i+1][j], abs(dp[i][(j+1)%2] - (j ? b[i] : a[i])));
    }
  }
  cout << min(dp[n][0], dp[n][1]) << endl;
  return 0;
}