#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#define popcount __builtin_popcount
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;

int main()
{
    int n; cin>>n;
    ll c[100010], d[100010];
    ll s=0;
    for(int i=0; i<n; i++){
        cin>>c[i]>>d[i];
        s+=c[i]+d[i];
    }
    ll dp[2];
    dp[1]=-d[0], dp[0]=-d[0]+c[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<<s+dp[0]<<endl;
    return 0;
}