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

char *opts(int, char **, char *);
int length(char *);

int main(int argc, char *argv[]) {
  printf("%s\n", opts(argc, argv, "shuder"));
  return 0;
}

int length(char *s) {
  int l = 0;
  while (*s) l++, s++;

  return l;
}

char *opts(int argc, char *argv[], char *o) {
  int i, z, j = 0, l = length(o);
  char *buffer = malloc(1024);

  if (argc < 2) return 0;
  for (i=1; i<argc; i++) {
    if (*argv[i] != '-') continue;
    for (; *argv[i]; (argv[i])++)
      for(z=0; z<l; z++)
        if (o[z] == *argv[i]) buffer[j] = *argv[i], j++;
  }

  buffer[j] = '\0';

  return (j) ? buffer : 0;
}