Conjecture

#include <bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define ld long double
#define M 100000007
#define N (1<<17)
#define P complex<long long>
#define X real()
#define Y imag()

using namespace std;

int n;

int main() {
	cin.tie(0);
	cout.tie(0);
	ios_base::sync_with_stdio(0);
	cin >> n;
	n++;
	if(n<=7)
		n=7;
	while(n%3==0)
		n++;
	cout << n;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED