Kolmijako

#include<bits/stdc++.h>
using namespace std;

int main(){
	int n;
	cin >> n;
	if(n % 6 == 1){
		cout <<"IMPOSSIBLE\n";
		return 0;
	}if(n % 6 == 2){
		cout << "2 3 ";
	}if(n % 6 == 3){
		cout << "1 2 3 ";
	}if(n % 6 == 4){
		cout << "IMPOSSIBLE\n";
		return 0;
	}if(n % 6 == 5){
		cout << "1 3 1 3 2 ";
	}
	if(n % 6 == 0){
		cout << "1 3 2 2 1 3 ";
	}
	for(int i = 0; i < n/6-(n%6==0); i++){
		cout << "1 2 3 3 2 1 ";
	}
	cout << "\n";
}

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 1, 2

Verdict: ACCEPTED

Test 3

Group: 1, 2

Verdict: ACCEPTED

Test 4

Group: 1, 2

Verdict: ACCEPTED

Test 5

Group: 1, 2

Verdict: ACCEPTED

Test 6

Group: 1, 2

Verdict: ACCEPTED

Test 7

Group: 1, 2

Verdict: ACCEPTED

Test 8

Group: 1, 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: ACCEPTED

Test 11

Group: 2

Verdict: ACCEPTED

Test 12

Group: 2

Verdict: ACCEPTED

Test 13

Group: 2

Verdict: ACCEPTED

Test 14

Group: 2

Verdict: ACCEPTED

Test 15

Group: 2

Verdict: ACCEPTED