暴力怎么说？

#include<bits/stdc++.h>
using namespace std;
int n;
int main(){
	cin>>n;
	if(n==4||n==7){
		cout<<-1;
		return 0;
	}
	if (n%5==0){
		cout << n/5;
	}
	else if(n%5==1){
		cout << n/5+1;
	}
	else if(n%5==2){
		cout << n/5+2;
	}
	else if(n%5==3){
		cout << n/5+1;
	}
	else{
		cout << n/5+2;
	}
    return 0;
}