#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
signed main() {
  ios::sync_with_stdio(false); cin.tie(0);
  int n;
  cin >> n;
  long long sum = 0;
  vector<long long> c(n), d(n);
  for (int i = 0; i < n; i++) {
    cin >> c[i] >> d[i];
    sum += c[i] + d[i];
  }
  vector<long long> dp(2);
  dp[0] = -d[0] + c[0];
  dp[1] = -d[0];
  for (int i = 1; i < n; i++) {
    dp[1] = min(dp[1], dp[0] - d[i]);
    dp[0] = min(dp[0], dp[1] + c[i]);
  }
  cout << sum + dp[0] << endl;
	return 0;
}