#include <bits/stdc++.h>
#define rep(i,n) for(int i=(0);i<(n);i++)

using namespace std;

typedef long long ll;

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);

	int n;
	cin >> n;

	ll asum = 0, bsum = 0;
	rep(i, n - 1){
		ll a, b;
		cin >> a >> b;
		asum += a;
		bsum += b;
	}

	cout << min(asum, bsum) + 1 << endl;
}