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

int main(int argc, char *argv[])
{
    if (argc > 0)
    {
        char *input = argv[1];
        int len = strlen(input);
        char *buf = malloc((len * sizeof(char)) + 1);
        int i = 0, j = 0;
        for (; i < len; i++)
        {
            char c = input[i];
            if (c >= 48 && c <= 57)
                buf[j++] = c;
        }
        buf[j] = '\0';

        printf("%s\n", buf);
        free(buf);
    }

    return 0;
}