History cf137C 读假题的危害猛女落泪 pair！

 #include<bits/stdc++.h>
using namespace std;
int main(){
    int n;cin>>n;
    vector<pair<int,int> > v(n);
    for(int i=0;i<n;i++){
        cin>>v[i].first>>v[i].second;
    }
    sort(v.begin(),v.end());

    int res=0;

    int start=v[0].first,end=v[0].second;

    for(int i=1;i<n;i++){
        if(v[i].first>start && v[i].second<end)res++;
        else {
            start=v[i].first;end=v[i].second;
        }
    }
    cout<<res;
}

#include<bits/stdc++.h>
using namespace std;
map<int, int> mp;
int main(){
    int n, x, y, far = 0, ans = 0; cin >> n;
    for(int i = 0; i < n; i++) {
        cin >> x >> y; 
        mp[x] = y;
    }
    for(auto [st, ed] : mp){
        if(far > ed) ans++;
        far = max(far, ed);
    }
    cout << ans;

    return 0;
}