activity_selection.cpp

#include<bits/stdc++.h>
using namespace std;
struct A
{
    int st,ed;
};
bool cmp(A &x, A &y)
{
    return (x.ed <y.ed);
}
int main()
{
    int n;
    cin>>n;
    vector<A>v(n);
    for(int i=0;i<n;i++)
    {
        cin>>v[i].st;
    }
    for(int i=0;i<n;i++)
    {
        cin>>v[i].ed;
}
    sort(v.begin(),v.end(),cmp);
    int last = v[0].ed,cnt=1;
    for(int i=1;i<n;i++)
    {
        if (v[i].st> last)
        {
            cnt++;
            last=v[i].ed;
        }
    }
    cout<<cnt<<endl;
    return 0;
}