Main.cpp

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main(void){
    // Here your code !
    unsigned int MAX_N=100000;
    unsigned int n;
    int s[MAX_N]; // source
    int t[MAX_N]; // sink
    cin >> n;
    cin.ignore();
    for(int i=0;i<n;i++){
        cin >> s[i];
    }
    cin.ignore();
    for(int i=0;i<n;i++){
        cin >> t[i];
    }
    
    vector<pair<int,int>> intervals(n);
    for(int i=0;i<n;i++){
        intervals[i].first = t[i];
        intervals[i].second = s[i];
    }
    sort(intervals.begin(), intervals.end());
    
    int count=0;
    int cursor=0;
    for(int i=0;i<n;i++){
        if(cursor<intervals[i].second){
            count++;
            cursor=intervals[i].first;
        }
    }

    cout << count << endl;

}