#include <stdio.h>

int main() {
	long long s = 0;
	char c = 0;
	while(1) {
		scanf("%c", &c);
		if(c == '\n') {
			break;
		}
		char index = 2 * (c - '0');
		long long current = (((s >> index) & 0xFF) + 1) << index;
		long long clear = ~(0xFF << index);
		s &= clear;
		s |= current;
	}
	
	while(s) {
		char last_num = 0;
		long long temp_s = s;
		while((temp_s = temp_s >> 2) > 0) {
			++last_num;
		}
		printf("%d", last_num);
		char index = 2 * last_num;
		long long current = (((s >> index) & 0xFF) - 1) << index;
		long long clear = ~(0xFF << index);
		s &= clear;
		s |= current;
	}
	
	return 0;
}