Words

#include <stddef.h>
#include <stdio.h>
#include <string.h>
int main() {
  const int n = 1024;
  char s1[n], *tok, *first = "";
  const char *s2 = " ,.\n";
  size_t len;
  fgets(s1, n, stdin);
  for (tok = strtok(s1, s2); tok; tok = strtok(NULL, s2)) {
    len = strlen(tok);
    if (len <= 2 || 7 <= len) continue;
    printf("%s%s", first, tok);
    first = " ";
  }
  printf("\n");
  return 0;
}