#include <stdio.h>
	#include <stdlib.h>
	#include <stdbool.h>
	#include <limits.h>
	#include <math.h>

	bool is_prime(unsigned long i) {
		if (i == 2)
			return true;
		if (i % 2 == 0)
			return false;
		unsigned int j;
		double root = sqrtl(i);
		for (j = 3; j < root; j += 2)
			if (i % j == 0)
				return false;
		return true;
	}

	int main(void) {
		
		char buffer[1025];
		while (fgets(buffer, 1025, stdin) != NULL) {
			unsigned long num;
			if (sscanf(buffer, "%lu", &num) != 1) {
				fprintf(stderr, "input a number!\n");
				continue;
			}

			if (is_prime(num) == true) {
				printf("%lu is prime.\n", num);
			} else {
				unsigned long i;
				for (i = num - 1; i >= 2; i--) {
					if (is_prime(i) == true) {
						printf("%lu < %lu < ", i, num);
						break;
					}
				}
				for (i = num + 1; i <= ULONG_MAX; i++) {
					if (is_prime(i) == true) {
						printf("%lu\n", i);
						break;
					}
				}
			}
		}

		return EXIT_SUCCESS;
	}