#include<iostream>
using namespace std;

int main(){
    int n;
    cin >> n;
    int asum = 0, bsum = 0;
    for(int i = 0; i < n-1; i++){
        int a, b;
        cin >> a >> b;
        asum += a, bsum += b;
    }
    cout << bsum+1 << endl;
    return 0;
}