#include <stdio.h>

int main() {
	char c;
	int cnt[10] = {}, i, j;

	while ((c = getchar()) != '\n') {
		cnt[c - '0']++;
	}
	for (i = 9; i >= 0; i--) {
		for (j = 0; j < cnt[i]; j++) {
			printf("%d", i);
		}
	}
	printf("\n");

	return 0;
}