Eratostene5

#include <bits/stdc++.h>
using namespace std;
ifstream f("eratostene5.in");
ofstream g("eratostene5.out");
bitset<1000005>pr;
vector<int>v;
int n,x,fr[1000005];
void ciur()
{
    pr[0]=pr[1]=1;
    for(int i=4; i<=1000000; i+=2)
        pr[i]=1;
    for(int i=3; i+i<=1000000; i+=2)
        if(!pr[i])
            for(int j=i+i; j<=1000000; j+=i)
                pr[j]=1;
    v.push_back(2);
    for(int i=3; i<=1000000; i+=2)
        if(!pr[i])
            v.push_back(i);
}
void desc(int n)
{
    int k=0;
    while(v[k]*v[k]<=n)
    {
        while(n%v[k]==0)
            n/=v[k],fr[v[k]]++;
        k++;
    }
    if(n>1)
        fr[n]++;
}
int main()
{
    ciur();
    f>>n;
    for(int i=1; i<=n; i++)
    {
        f>>x;
        desc(x);
    }
    for(int i=0; i<v.size(); i++)
        if(fr[v[i]])
            g<<v[i]<<" "<<fr[v[i]]<<"\n";
    return 0;
}