Conjecture

#include <stdio.h>
#include <iostream>
#include <memory.h>
#include <string>
#include <algorithm>
#include <vector>
using namespace std;

#define sqr(a) ((a) * (a))
#define pi 3.1415926535897932384626433832795

#define TASK "b"
int n;

void Load()
{
	cin >> n;
}

void Solve()
{
	if (n < 7) cout << 7;
	else 
	{
		if ((n+1)%3 == 0)
			cout << n+2;
		else
			cout << n+1;
	}
}

int main()
{
#ifdef CONTEST
	freopen(TASK".in", "r", stdin);
	freopen(TASK".out", "w", stdout);
#endif
	
	Load();
	Solve();

	return 0;
}

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