#include <stdio.h>

int main()
{
    int n;
    scanf(" %d", &n);
    printf("%d\n", (n + 2) / 3);
    return 0;
}

 #include

int main()
{
    int n;
    scanf(" %d", &n);
    printf("%d\n", (n + 2) / 3);
    return 0;
}

 

LOL