#include<stdio.h>
int minTurns(int n)
{
    if (n == 0) return 0;
    if (n < 0) return 1000;
    int a = minTurn(n - 1);
    int b = minTurn(n - 2);
    int c = minTurn(n - 3);
    int min = a < b ? (a < c ? a : c) : (b < c ? b : c);
    return 1 + min;
}
int main()
{
    float x;
    scanf("%f",&x);
    int n = (int)x;
    if (x < 0 || x != n)
    {
        printf("Invalid Input\n");
        
    }
    else
    {
        printf("%d\n",minTurns(n));
        
    }
    return 0;
}