#include<bits/stdc++.h>
using namespace std;
using ll=long long;
#define rep(i,p,n)for(ll i=(ll)p;i<(ll)n;i++)
#define all(x)(x).begin(),(x).end()
#define edt(x1,y1,x2,y2)sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2))
int main(){
	ll X;
	cin>>X;
	vector<string> vec={"A","A","B","B","A","B","B"};
	ll ans=0,pos=0,cnt=0;
	while(pos!=X){
		if(vec[cnt%7]=="A"){
			pos+=2;
			ans+=2;
		}
		else{
			pos-=1;
			ans+=1;
		}
		cnt++;
	}
	cout<<ans<<endl;
}