// not uniq(1)

#include <stdint.h>
#include <stdio.h>
#include <ctype.h>

const char *unique(const char *str, const char **dup) {
  const char *alphabet[26] = { NULL };

  for(; *str; str += 1) {
    uint8_t pos = tolower(*str) - 'a';

    if(pos >= 0 && pos <= 25) {
      if(alphabet[pos]) {
        *dup = str;
        return alphabet[pos];
      } else {
        alphabet[pos] = str;
      }
    }
  }

  return NULL;
}

int main(int argc, char **argv) {
  const char *str = "";

  if(argc > 1) {
    str = argv[1];
  }

  const char *dup = NULL;
  const char *idx = unique(str, &dup);

  if(dup) {
    uint8_t idx_spacing = (int) (idx - str) + 1;
    uint8_t dup_spacing = (int) (dup - str) - idx_spacing + 1;
    printf("%s\n%*s%*s\n", str, idx_spacing, "^", dup_spacing, "^");
  }

  return 0;
}