#include<stdio.h>
int minTurns(int score) {
    if (score < 0) return-1; // Invalid
    if (score == 0) return 0;
    int t1 = minTurns(score-1);
    int t2 = minturns(score-2);
    int t3 = minturns(score-3);
    int min = t1;
    if(t2 < min)min = t2;
    if(t3 < min)min = t3;
    return 1 + min;
    }
    int main()
    {
        float input;
        scanf("%f",&input);
        int score = (int)input;
        if score < 0)
              printf("Invalid input\n");
        else
              printf("%d\n",minTurns(score));
              return 0;
    }
}