Can someone please say why the hell is it wrong?:(

#include<iostream>

using namespace std;

int main()
{
    const int size=10;
    int pro[10]={0};
    long long int magic=1;
    int licz=2;
    const int n=10000;
    bool numbersTable[n+1]={0};
    int pierw[1229];
    int w=0;
    //sito

        for (int i = 2; i <= n; i++ )
        {
                if (numbersTable[i] == true) continue;
                pierw[w++]=i;
                for (int j = 2 * i ; j <= n; j += i)
                        numbersTable[j] = true;
        }


    for(int i=0;i<size;i++)
    {
        cin>>pro[i];
        magic*=pro[i];
    }

    int k=0;
    long long int z=0;
    licz=1;
    for(int i=0; i<1229; i++)
    {

        if(magic/pierw[i]<1) break;
        k=0;
        z=magic;
        while(z%pierw[i]==0)
        {

            z/=pierw[i];
            k++;
        }
        licz*=(k+1);


    }

    if (magic==1) licz=1;

    cout << licz%10;



}

Dear friend:
Is not necessary multiply the input, working each a_i you can reduce the complexity