小狐狸的X · 发布于 2022-10-21 · 浏览 673 回复 0

//freopen("1114.in","r",stdin);
//freopen("1114.out","w",stdout);
int n;
scanf("%d",&n);
if(n%3==0&&n%7==0){
	printf("%d",n/7);
}else{
	printf("-1");
}
return 0;