#include<stdio.h>
void era(int max,int a[1000001])
{
    for(int i=2;i<=max;i++)
        if(a[i]==0)
        for(int j=i+i;j<=max;j=j+i)
        a[j]=1;
}
int cop(int a,int b)
{
    while(b)
    {
        int r=a%b;
        a=b;
        b=r;
    }
    return a;
}
int b[100001],era1[1000001];
int main()
{
    FILE*f=fopen("pairs.in","r");
    FILE*g=fopen("pairs.out","w");
    int a,c,max=0,x,y,s=0;
    fscanf(f,"%d",&a);
    for(int i=1;i<=a;i++)
    {
        fscanf(f,"%d",&c);
        if(c>1&&c<1000000)
            b[i]=c;
        if(b[i]>max)
            max=b[i];
    }
    era(max,era1);
    c++;
    int t,t1;
    for(int i=1;i<a;i++)
        for(int j=1+i;j<=a;j++)
        {
            x=b[i];
            y=b[j];
            if(x>y)
            {
             t=x;
             t1=y;
            }
            else
            {
                t=y;
                t1=x;
            }
            if(era1[x]==0&&era1[y]==0)
                s++;
            else if(((era1[x]==0&&era1[y]==1)||(era1[x]==1&&era1[y]==0))&&t%t1!=0)
                s++;
            else if(x==y+1||x==y-1)
                s++;
            else
                if(cop(x,y)==1)
                    s++;
        }
        fprintf(g,"%d",s);
}