#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdint.h>
int main(int argc, char **argv) {

  long unsigned long a = 0;
  long unsigned long c = 0;
  long unsigned long g = 0;
  long unsigned long t = 0;

  if(argc != 2) {
    printf("Please supply a filename, and only a filename\n");
    exit(EXIT_FAILURE);
  }
  FILE *fh = fopen(argv[1], "r" );
  if(fh == NULL) {
    fprintf(stderr, "could not open dna.txt\n");
    exit(EXIT_FAILURE);
  }

  unsigned int ch = 0;
  while ((ch = getc(fh)) != EOF) {
    switch(ch) {
      case 'A':
      case 'a':
        a++;
        break;
      case 'C':
      case 'c':
        c++;
        break;
      case 'G':
      case 'g':
        g++;
        break;
      case 'T':
      case 't':
        t++;
        break;
    }
  }

  printf("A:%llu\nC:%llu\nG:%llu\nT:%llu\n", a, c, g, t);

  return EXIT_SUCCESS;
}