erastoten

void erastoten(bool arb[], ll n){
    prime.push_back(2);
    arb[2] = true;

    for(ll chk = 2; chk < n; chk++){
        if(!arb[chk]) continue;
        if(chk != 2){
            prime.push_back(chk);
            arb[chk] = true;
        }

        for(ll i = chk + 1; i < n; i++){
            if(arb[i]){
                if(i % chk != 0) arb[i] = true;
                else arb[i] = false;
            }
        }
    }
}

void setbool(bool* arb, ll n){
    for(ll i = 0; i < n; i++){
        if(i % 2 == 0) arb[i] = false;
        else arb[i] = true;
    }
}


void prtvec(const vector<long long> vec){
    for(unsigned i = 0; i < vec.size(); i++){
        cout << vec.at(i);
        if(i < vec.size()-1) cout << ", ";
    }
}