Better Sparse Table

#include <iostream>
#include <cmath>
#include <vector>
#include <set>
#include <string>
#include <algorithm>
using namespace std;
using ll = long long;
using unt = unsigned int;
void cv(vector <unt> v){
    for (auto x: v) cout<<x<<' ';
    cout<<'\n';
}

vector <unt> ar(1);

vector <pair<unt,unt>> qr(1);

unt sm;

vector <vector <unt> > wrk;

vector <unt> power;

void make(){
    int lvl = 1,l,r;
    //cout<<"sz= "<<ar.size()<<'\n';
    while (pow(2,lvl) <= ar.size()){
            //cout<<"lvl = "<<lvl<<'\n';
        vector <unt> last = wrk[wrk.size() - 1];
        int len = pow(2, lvl);
        int hlf = len / 2;
        for (int i = 0; i<=ar.size()-len; ++i){
           // cout<<"i = "<<i<<'\n';
            l = i;
            r = i + len - 1;
            unt L = last[l];
            unt R = last[l+hlf];
            sm = min(L, R);
            power.push_back(sm);
        }
        wrk.push_back(power);
        power.clear();
        lvl++;
    }
}
int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    unt N,M,A,B;
    while (true){
        cin>>N>>M>>A>>B;
        if (N==0 && M==0 && A==0 && B==0) break;
        ar.clear();
        qr.clear();
        unt d;
        unt d1, d2;
        for (int i = 1;i<=N+M*2;++i){
            if (i <= N){
                d = A * i + B;
                ar.push_back(d);
            }
            else{
                d1 = (A * i + B);
                d1 %= N;
                d1++;
                i++;
                d2 = (A * i + B);
                d2 %= N;
                d2++;
                //cout<<"d1d2= "<<d1<<' '<<d2<<'\n';
                qr.push_back({d1, d2});
            }
        }
        for (int i = 0; i < ar.size();++i){
            sm = ar[i];
            power.push_back(sm);
        }
        wrk.push_back(power);
        power.clear();
        make();
        ll ans;
        ll tot = 0;
        /*cout<<"qr:\n";
        for (auto x: qr) cout<<x.first<<' '<<x.second<<'\n';
        cout<<'\n';*/
        for (auto Q: qr){
            unt a = min(Q.first, Q.second);
            unt b = max(Q.first, Q.second);
            a--;
            b--;
            //cv(ar);
            //cout<<"ab= "<<a<<' '<<b<<'\n';
            unt LVL = floor(log(b-a+1) / log(2));
            vector <unt> now = wrk[LVL];
            ll lft = now[a];
            ll rgt = now[b - pow(2,LVL) + 1];
            ans = min(lft, rgt);
            //cout<<"ans= "<<ans<<'\n';
            tot += ans;
        }
        cout<<tot<<"\n";
        wrk.clear();
    }

}