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

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int N; cin >> N;
    vector<int> T(N),S(N);
    for(auto &t : T) cin >> t;
    for(auto &s : S) cin >> s;
    int answer = 0,back = 0;
    for(int i=0; i<N; i++){
        if(S.at(i) >= back) answer++,back = S.at(i)+T.at(i); 
    }
    cout << answer << endl;
}