private int c2I(char c) {
        int x = 0;
        switch (c) {
            case 'A': x = 0;
                      break;
            case 'C': x = 1;
                      break;
            case 'G': x = 2;
                      break;
            case 'T': x = 3;
                      break;
            default: x = 0;
                     System.out.println("Couldn't convert char "+c+" to index");
                     break;
        }
        return x;
    } // Method - charToIndex