#include <fstream>
#define N 500001
using namespace std;
ifstream fin ("eratostene1.in");
ofstream fout ("eratostene1.out");
bool ciur[N];
int n,i,x,j;
int ct=0;
int main()
{
    ///ciur
    for(int i=1;i<N;i++)
        if(ciur[i]==0)
         for(j=3*i+1;j<N;j+=(i<<1)+1)
           ciur[j]=1;
    fin>>n;
    while(n--)
    {
        fin>>x;
        if(x==2) x++;
        if(x%2==1)
             ct+=1-ciur[(x>>1)];
    }
    fout<<ct;
    return 0;
}