/* pos is the amount of correct positions in the string size */
    int pos = 0, fail = 0;
    for(int i = 0; i < 4; i++) {
        /* pos is sum of minor occurrences of a DNA segment */
        if(dna1[i] > dna2[i]) pos += dna2[i];
        else pos += dna1[i];
    }
    /* s-pos is the amont of incorrect occurrences regardless of
     * permutations, if the amount is higher than the error margin
     * then we failed */
    if(s-pos > n) fail = 1;