#include <stdio.h> int main() { int n; scanf("%d",&n); int a = n % 8; int b = a % 6; int num; if(a == 0) { num = n / 8; printf("%d\n",num); return 0; } if((a != 0) && (b == 0)) { num = ((n - a) / 8) +1; printf("%d\n",num); return 0; } if(a == 4) { num = n / 8 + 1; printf("%d\n",num); return 0; } if(a == 2) { num = n / 8 + 1; printf("%d\n",num); return 0; } printf("-1"); return 0; }