#include <stdio.h>
#include <inttypes.h>
#include <assert.h>

const uint32_t N = 100000000;
const uint32_t M = 12, Z = 26, H = M + 1;

static const char* mnames[M + 1] = {
	"",
	"Jan",
	"Feb",
	"Mar",
	"Apr",
	"May",
	"Jun",
	"Jul",
	"Aug",
	"Sep",
	"Oct",
	"Nov",
	"Dec"
};


static const uint32_t mhash[H] = {0, 2, 6, 1, 10, 4, 7, 11, 3, 8, 9, 12, 5};

uint32_t month_to_num(const unsigned char *s)
{
	uint32_t c0 = s[0] - 'A';
	if (Z <= c0)
		return 0;
	uint32_t c1 = s[1] - 'a';
	if (Z <= c1)
		return 0;
	uint32_t c2 = s[2] - 'a';
	if (Z <= c2)
		return 0;
	if (s[3])
		return 0;
	uint32_t z = ((1431655833 * c2) ^ c1) % H;
	if (z == 0)
		return z;
	z = mhash[z];
	assert (0 < z && z <= M);
	const unsigned char *s0 = (const unsigned char *) mnames[z];
	if (s[0] != s0[0] || s[1] != s0[1] || s[2] != s0[2])
		return 0;
	return z;
}


int main()
{
	uint32_t acc = 0;
	for (uint32_t j = 0; j < N; j++) {
		for (uint32_t i = 0; i <= M; i++) {
			acc += month_to_num((const unsigned char*) mnames[i]);
		}
	}

	printf("acc = %u \n", acc);
	for (uint32_t i = 0; i <= M; i++) {
		uint32_t z = month_to_num((const unsigned char*) mnames[i]);
		printf("%3s %2u %2u \n", mnames[i], z, i);
	}

	return 0;
}