WA IN GAME3 SPOJ

Here is the link of the problem http://www.spoj.com/problems/GAME3/

#include
using namespace std;

int main()
{
unsigned long long n, ctr, a, c, d, i;

int t;

char x[15] = { ‘m’, ‘i’, ‘m’, ‘m’, ‘i’, ‘m’, ‘i’, ‘i’, ‘m’, ‘i’, ‘m’, ‘i’, ‘m’, ‘i’, ‘m’ };

cin >> t;
while (t--)
{
	cin >> n;
	a = (n-2) / 15;
	c = n-a*15;
	if (x[c-2] == 'm')
		cout << "Marica\n";
	else
		cout << "Ivica\n";
}
return 0;

}

for n = 6, Marica will win in any case. What was your approach and can you prove that pattern repeats after 15?