#include using namespace std; typedef long long ll; int main(){ int n;cin >> n; vector a(n),b(n); int sa=0,sb=0; for(int i=1;i> a[i] >> b[i]; sa+=a[i],sb+=b[i]; } if(sasb){ cout << sb+1 << endl; } else{ cout << sb+1 << endl; } }