Contest Problem G

#include <bits/stdc++.h>
#define MAX 100000
#define ll   long long

using namespace std;
vector<long long int> smallprimes;

void sieve() {
    bool isPrime[MAX];
    for (ll i = 0; i < MAX; i++) isPrime[i] = true;
    for (ll i = 3; i * i <= MAX; i += 2)
        if (isPrime[i])
            for (ll j = i * i; j < MAX; j += i)
                isPrime[j] = false;
    smallprimes.push_back(2);
    for (ll i = 3; i < MAX; i += 2)
        if (isPrime[i]) smallprimes.push_back(i);
}

void segSieve (ll lower,ll upper) {
    bool isPrime[1000010];
    for (ll i = 0; i <= upper - lower ; i++) isPrime[i] = true;
    if (lower == 1) isPrime[0] = false;
    for (ll i = 0; smallprimes[i]*smallprimes[i] <= upper; i++) {
        ll cur = smallprimes[i];
        ll base = (lower/cur)*cur;
        if (base < lower) base += cur;
        for (ll j = base; j <= upper; j += cur)
            isPrime[j-lower] = false;
        if (base == cur) isPrime[base-lower] = true;
    }
    ll dif,min_dif=1000010,max_dif=0,mnv1,mnv2,mxv1,mxv2,curitem;
    bool check=true;
    //for (ll int i=0;i<upper-lower-1;i++)
    //{2111111207,2111111209 are closest, 2111111213,2111111291 are most distant.

      //  if(isPrime[i]) cout<<i+lower<<endl;
    //}



     for (ll i = 0; i < upper - lower + 1; i++) {
        if ( check && isPrime[i]){
            curitem=i+lower;
            //cout<<"First curitem = "<<curitem<<endl;
            check=false;
            continue;
        }
        if (isPrime[i]){
            dif=(i+lower)-curitem;
            //cout<<"Curitem  = "<<curitem<<" Dif = "<<dif<<endl;
            if (dif>max_dif){
                max_dif=dif;
                mxv1=curitem;
                mxv2=i+lower;
            }
            if (dif<min_dif){
                min_dif=dif;
                mnv1=curitem;
                mnv2=i+lower;
            }
            curitem=i+lower;
        }
    }
    if (max_dif==0) cout<<"There are no adjacent primes."<<endl;
    else cout<<mnv1<<","<<mnv2<<" are closest, "<<mxv1<<","<<mxv2<<" are most distant."<<endl;
}



int main() {

    sieve();
    ll int l, u;
    while(cin>>l>>u) {
        segSieve(l,u);
    }
}