#include <stdio.h>
#include <stdlib.h>
#include <string.h>

long long int P = 192754319;
long long int Q = 613463863;
long long int S = 427419669081;

long long int M;

int is_good_prime (long long int p)
{
	long long int t;
	if (p < 2)
		return 0;
	if (p % 4 != 3)
		return 0;
	if (p < 4)
		return 1;
	for (t=3; t*t <= p; t += 2) {
		if (p % t == 0)
			return 0;
	}
	return 1;
}

long long phi (long long v) {
	long long ret = 1;
	long long t = 2;
	while (v > 1) {
		if (t*t > v) {
			ret *= v-1;
			break;
		}
		if (v % t == 0) {
			ret *= t-1;
			v /= t;
		}
		while (v % t == 0) {
			ret *= t;
			v /= t;
		}
		t++;
	}
	return ret;
}

long long int gcd (long long int a, long long int b)
{
	while (a && b) {
		if (a > b) {
			a %= b;
		} else {
			b %= a;
		}
	}
	return a+b;
}

void init (void)
{
	if (!is_good_prime (P) || !is_good_prime (Q)) {
		fprintf (stderr, "WARNING: One of the primes in bad\n");
		exit (1);
	}
	if (gcd (phi(P-1), phi(Q-1)) > 10) {
		fprintf (stderr, "WARNING: The gcd of P-1 and Q-1 is large\n");
		exit (1);
	}
	M = P*Q;
}

int get (int decrypt)
{
	long long ret = S % 26LL;
	if (decrypt) {
		ret = 26-ret;
	}
	/* Die folgenden Schleife berechnet (S*S) % M ohne Ueberlauf in
	 * long long, falls S und M in ca. 62 Bit darstellbar sind.
	 * Nur fuer Beispieltext 3 notwendig. */
	long long f1 = S, f2 = S;
	S = 0;
	while (f1) {
		if (f1 % 2LL) {
			S += f2;
			S %= M;
		}
		f1 /= 2LL;
		f2 *= 2LL;
		f2 %= M;
	}
	return ret;
}

void usage (char * p)
{
	fprintf (stderr, "usage: %s [-e | -d ] P Q S\n", p);
	exit (1);
}

int main (int argc, char * argv[])
{
	int ch;
	int decrypt = -1;
	char dummy;

	/* ARGUMENTVERARBEITUNG: Einlesen von P, Q und S. War nicht verlangt */
	if (argc != 5) {
			usage (argv[0]);
	}
	if (strcmp (argv[1], "-e") == 0) {
		decrypt = 0;
	}
	if (strcmp (argv[1], "-d") == 0) {
		decrypt = 1;
	}
	if (sscanf (argv[2], "%lld%c", &P, &dummy) != 1) {
		usage (argv[0]);
	}
	if (sscanf (argv[3], "%lld%c", &Q, &dummy) != 1) {
		usage (argv[0]);
	}
	if (sscanf (argv[4], "%lld%c", &S, &dummy) != 1) {
		usage (argv[0]);
	}
	/* Ende Argumentverarbeitung */
	init ();
	while (1) {
		ch = getchar ();
		if (ch < 0)
			break;
		switch (ch) {
		case 'a' ... 'z':
			ch = 'a' + (ch-'a'+get(decrypt)) % 26;
			break;
		case 'A' ... 'Z':
			ch = 'A' + (ch-'A'+get(decrypt)) % 26;
			break;
		default:
			;
		}
		printf ("%c", ch);
	}
	return 0;
}