#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < (n);i++)
#define sz(x) int(x.size())
typedef long long ll;
typedef pair<int,int> P;

int main(){
  int n;
  cin >> n;
  int sum_a = 0, sum_b = 0;
  rep(i,n-1){
    int a, b;
    cin >> a >> b;
    sum_a += a;
    sum_b += b;
  }
  int res = 0;
  rep(i,sum_a){
    rep(j,sum_b) if (abs(i - j) == abs(sum_a - sum_b)) res++;
  }
  cout << ++res << endl;
  return 0;
}