#include <iostream>
#include <vector>

using namespace std;

const int N=7;

int main(){
    int n;
    cin>>n;

    vector<int> ar(N, 0);

    for(int i=0;i<n;i++){
        int a;
        cin>>a;
        ar[a%N]++;
    }

    int ans=ar[0]*(ar[0]-1)/2;

    for(int i=1;i<(N+1)/2;i++){
        ans+=ar[i]*ar[N-i];
    }

    if(N%2==0){
        ans+=ar[N/2]*(ar[N/2]-1)/2;
    }

    cout<<ans;
}