#include<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<iomanip>
#include<math.h>
#include<complex>
#include<queue>
#include<deque>
#include<stack>
#include<map>
#include<set>
#include<bitset>
#include<functional>
#include<assert.h>
#include<numeric>
using namespace std;
#define REP(i,m,n) for(int i=(int)(m) ; i < (int) (n) ; ++i )
#define rep(i,n) REP(i,0,n)
using ll = long long;
const int inf=1e9+7;
const ll longinf=1LL<<60 ;
const ll mod=1e9+7 ;

int main(){
    int n;
    cin>>n;
    ll x[n],y[n];
    ll ans = 0;
    rep(i,n){
        cin>>x[i]>>y[i];
        ans+=x[i]+y[i];
    }
    ll dp[2];
    dp[0]=x[0]-y[0];
    dp[1]=-y[0];
    REP(i,1,n){
        ll ndp[2];
        ndp[0]=min({dp[0]+x[i]-y[i],dp[1]+x[i]});
        ndp[1]=min(dp[1],dp[0]-y[i]);
        dp[0]=min(dp[0],ndp[0]);
        dp[1]=ndp[1];
    }
    cout<<ans+dp[0]<<endl;
    return 0;
}