private void getBrain() {
		while(antBrain!=null && readAhead!=-1) {
			char read = (char) readAhead;
			readNext();
			switch(read) {
			case'D': case'd':
				getDropInstruction();
				break;
			case'F': case'f':
				getFlipInstruction();
				break;
			case'M': case'm':
				read = (char) readAhead;
				if(read=='a' || read=='A') {
					readNext();
					getMarkInstruction();
				} else if(read=='o' || read=='O') {
					readNext();
					getMoveInstruction();
				} else {
					error(read, "a or o");
				}
				break;	
			case'P': case'p':
				getPickupInstruction();
				break;
			case'S': case's':
				getSenseInstruction();
				break;
			case'T': case't':
				getTurnInstruction();
				break;
			case'U': case'u':
				getUnmarkInstruction();
				break;
			default:
				error("did not identify an instruction, found " + read);
				break;
			}
		}
	}