#include<iostream>
#include<algorithm>
#include<string>
#include<math.h>
#include<bitset>
#include <vector>
#include<bitset>
#include <iomanip>
#include <map>
#include <set>
#include <stack>
#include <deque>
#include <climits>
#include <queue>
using namespace std;

int main() {
	

	int N;
	cin >> N;
	int A[50], B[50];
	for (int i = 2; i <= N; i++)cin >> A[i] >> B[i];
	int answer = 0;
	for (int i = 2; i <= N; i++)answer = answer + B[i];
	cout << answer + 1;


}