/*#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
set<ll> simpl(ll s){
    set<ll> lll;
    for (ll i=2; i<s; i++){
        if (s%i==0){
            lll.insert(i);
        }
    }
    return lll;
}
int main(){
    for (ll n=0; n<10000; n++) {
        cout << n << ':';
        for (auto& j:simpl(n*n*n*n+n*n+1))
            cout << j << ',';
        cout << endl;
    }
    return 0;
}*/


/*#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int main(){
    double s1=1774, s2=1899;
    for (int i=3; i<2108; i++)
    {
        double s3;
        s3=(double)((double)s2+1.0)/s1;
        cout << i << " : " << s3 << endl;
        s1=s2;
        s2=s3;
    }
    return 0;
}*/
#include <bits/stdc++.h>
    #include <ctime>
using namespace std;
typedef long long ll;
int main(){
    ll count=0;
    ll poscount=0;
    srand(time(0));
    for (int i=3; i<100000; i++)
    {
        set<ll> sett {0,1,2,3,4,5,6};
        bool au[7] {};
        bool b=false;
        if ((rand() % 10)>2)
            au[rand()%7]=true;
        ll h=rand()%7;
        sett.erase(h);
        for(auto&k:sett){
            if (au[k]){
                b=true;
                break;
            }
        }
        if (!b)
            if (au[h]){
                poscount++;
                count++;
            }
            else
                count++;
    }
    //cout << poscount << ' ' << count;
    cout << (double)poscount*1.0/count;
    return 0;
}