public static int numLetters(AlignmentTriplet triplet) {
	FlaggableCharacterString _p = triplet.getPresented();
	FlaggableCharacterString _t = triplet.getTranscript();
	FlaggableCharacterString _i = triplet.getInputstream();
	IsLetterCondition is = new IsLetterCondition();
	
	int num = 0;
	for(int i = 0; i < _i.size(); i++) {

	    if(is.applies(_p.get(i)) && _p.get(i).getErr() != null) {
		num++;
	    }
	    if(is.applies(_t.get(i)) && _t.get(i).getErr() != null) {
		num++;
	    }
	    if(is.applies(_i.get(i)) && _i.get(i).getErr() != null) {
		num++;
	    }
	}
	return num;
    }