activity.cpp

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

bool cmp(pair<int, int> a, pair<int, int> b) {
    return a.second < b.second;
}

int main(int argc, char const *argv[])
{
    int t;
    cin>>t;
    while(t--) {
        int n, a, b;
        cin>>n;
        pair<int, int> arr[n];
        for(int i=0;i<n;i++) {
            cin>>a>>b;
            arr[i] = make_pair(a, b);
        }
        sort(arr, arr+n, cmp);
        // for(int i=0;i<n;i++) {
        //  cout<<arr[i].first<<" "<<arr[i].second<<endl;
        // }
        int ans = 1, chosen = 0;
        for(int i=1;i<n;i++) {
            if(arr[i].first>=arr[chosen].second) {
                ans++;
                chosen = i;
            }
        }
        cout<<ans<<endl;
    }
    return 0;
}