#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<n;i++)
using namespace std;
typedef long long ll;
typedef pair<int,int> pp;
const int INF = 1e9;
const int MOD = 1000000007;


int main() {
    int n;
    cin >> n;
    int a_sum = 0,b_sum = 0;;
    vector<int> a(n-1),b(n-1);
    rep(i,n-1){
        cin >> a[i] >> b[i];
        a_sum += a[i];
        b_sum += b[i];
    }
    int m = 0;
    rep(i,n-1){
        m = max(m,a[i]+b[i] - a_sum);
    }

    cout << b_sum + 1 - m << endl;

    return 0;  
}