#include <cstdio>
#include <cstring>

typedef unsigned int uint;

int main() {
	const size_t LEN = 1e6 + 10;
	char* line = new char[LEN];
	
	while (true)
	{
		line[0] = '0';
		line[1] = '0';
		line[2] = '0';
		line[3] = '0';
		if (NULL == fgets(line + 4, LEN - 4, stdin))
			return 0;
		
		size_t len = strlen(line);
		if (line[len - 1] == '\n')
			line[--len] = '\0';
		if (len == 0)
			return 0;
		
		for (uint i = 0; i < (len + 1) / 2; ++i)
		{
			char* p = line + len - (i + 1) * 2;
			char* q = p + 1;
			if (*p == '1')
			{
				if (*q == '0')
					*q = '1';
				else // if (*q == '1')
				{
					*p = '0';
					*q = '0';
				}
			}
			else // if (*p == '0')
			{
				if (*q == '0')
					*q = '1';
				else // if (*q == '1')
				{
					*p = '1';
					*q = '0';
					continue;
				}
			}
			break;
		}
		
		char* r = line;
		while (*r == '0')
			++r;
		printf("%s\n", *r == '\0' ? (r - 1) : r);
	}
}