有何区别？

#include<bits/stdc++.h>
using namespace std;
int n;
int main()
{
    vector<int> a;
    int x;
    while(cin>>x){
        a.push_back(x);
        n++;
    }
    reverse(a.begin(),a.end());
    vector<int> t;
    t.clear();
    for(auto e:a){
        auto it=upper_bound(t.begin(),t.end(),e);
        if(it==t.end()) t.push_back(e);
        else *it=e;
    }
    cout<<t.size()<<endl;
    t.clear();
    reverse(a.begin(),a.end());
    for(auto e:a){
        auto it=upper_bound(t.begin(),t.end(),e);
        if(it==t.end()) t.push_back(e);
        else *it=e;
    }
    cout<<t.size()<<endl;
    return 0;
}