不用if也能解！

#include<bits/stdc++.h>
#define int long long
#define INF 0x3f3f3f
using namespace std;
int n;
signed main(){
	cin>>n;
	cout<<-(n%2)*3+6;
	return 0;
}

Python :

# coding=utf-8
a=int(input())
if a//2:
    print('6')
else:
    print('3')