#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdint.h>
main() {

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

FILE *fh = fopen("dna.txt", "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:%lu\nC:%lu\nG:%lu\nT:%lu\n", a, c, g, t);
}