UVa 11150 - Cola

//\\__ hr1212 __//\\

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef pair<int,int> pii;
typedef map<int,int> mi;

#define si(a) scanf("%d",&a)
#define sii(a,b) scanf("%d %d",&a,&b)
#define siii(a,b,c) scanf("%d %d %d",&a,&b,&c)
#define pi(a) printf("%d\n",a)
#define nl printf("\n");
#define pb push_back
#define mp make_pair
#define all(c) (c).begin(),(c).end()
#define f(i,a,b) for(i=a;i<b;i++)
#define rf(i,a,b) for(i=a;i>=b;i--)
#define clr(x,a) memset(x,a,sizeof(x))
#define MAX 1000100
#define MOD 1000000007

int n,m;

int solve(int n,int tk){
    int ans=n-tk;
    while(n>2){
        ans+=n/3;
        n=n/3+n%3;
    }
    if(tk>n)
        ans=0;
    return ans;
}

int main(){
    int tk,rem,r,k,i,c=0,x=0,y=0,j,t,l,z,x1=0,y1=0;
    ll ans=0;string p;

    while(si(n)!=EOF){
        pi(max(solve(n,0),max(solve(n+1,1),solve(n+2,2))));
    }
    return 0;
}