public int takeExpression(String input,int pos)
	{
		int pos1 = pos;
		if(isTerm(input,pos)){
			pos = takeTerm(input,pos);
			int pos2 = pos;
			if(isPlusMinus(input,pos)){
				pos = takePlusMinus(input,pos);
				if(isTerm(input,pos)){
					return takeTerm(input,pos);}
			}
			return pos2;
			}
		
		return pos1;
	}