Prime Distance - inconcluso

#include <iostream>
#include <cstring>
#include <vector>
#include <cmath>
using namespace std;
const long long N =100000000;

bool esPrimo[N];
void criba(long long ini,long long n){
    for (long long i=0;i<=n;i++) esPrimo[i]=true;

    esPrimo[0]=esPrimo[1]=false;

    for (long long p=ini;p<=n;p++){
        if (esPrimo[p])
            for(long long mul=p*p;mul<N;mul+=p) esPrimo[mul]=false;
    }
}
int numgrandeEsPrimo(long long n){
    long long tope=((long long) pow(n,0.5)) +1;
    //cout<<"tope: "<<tope<<endl;
    for (long long i=2;i<=tope;i++){
        if ((n % i) ==0){
            return 0;}
    }
    //cout<<n<<" es primo"<<endl;
    return 1;
}

int main(){

    long long l,u,uant=-1;
    criba(2,100000000);
    while(cin>>l>>u){
        long long d1=-1,d2=-1,c1=-1,c2=-1,ant,difmin=u,difmax=0;
        for(long long i=l;i<=u;i++){
            if (esPrimo[i]){
                if (d1==-1)
                    d1=i;
                else{
                    if ((i-ant)>difmax){
                        d1=ant;d2=i;difmax=d2-d1;
                    }
                }
                if (c1==-1)
                    c1=i;
                else{
                    if ((i-ant)<difmin){
                        c1=ant;c2=i;difmin=c2-c1;
                    }
                }
                ant=i;
            }
        }
        if(c2!=-1)
            cout<<c1<<','<<c2<<" are closest, ";
        if(d2!=-1)
            cout<<d1<<','<<d2<<" are most distant."<<endl;
        else
            cout<<"There are no adjacent primes."<<endl;
    }


    return 0;
}