#include <bits/stdc++.h>
using namespace std;

int main() {
    int n;
    cin >> n;

    int inSum = 0;   // ->
    int outSum = 0;  // <-
    for (int i = 0; i < n - 1; ++i) {
        int in, out;
        cin >> in >> out;
        inSum += in;
        outSum += out;
    }
    // int ans = inSum - (inSum - min(inSum, outSum)) + 1;
    cout << min(inSum, outSum) + 1 << endl;
}