How do I number the nodes, if they are sometimes different elements

I need to number the nodes that contain data (xml) using xsl transformation. Nodes that are numbered, may have elements with different tag names. I was looking for a solution to this, but I could not find a proper way of numbering.

Here is a sample input file:

       <Contract>
        <Parametr1>
            <Interposes>
                   <Accomplice>
                    <Person>
                        <Name>John</Name>
                           <Surname>Person1</Surname>
                    </Person>
                   </Accomplice>
                <Representative>
                    <Name>George</Name>
                    <Surname>Person2</Surname>
                   </Representative>
            </Interposes>
            <Interposes>
                <Accomplice>
                    <Person>
                        <Name>Andy</Name>
                        <Surname>Person3</Surname>
                    </Person>
                </Accomplice>
            </Interposes>
            <Interposes>
                <Accomplice>
                    <Firm>
                        <FirmName>VeloDrom</FirmName>
                        <Description>Description</Description>
                    </Firm>
                </Accomplice>
                <Representative>
                    <Name>Agnes</Name>
                    <Surname>Person4</Surname>
                </Representative>
                <Representative>
                    <Name>Michael</Name>
                    <Surname>Person5</Surname>
                </Representative>
            </Interposes>
        </Parametr1>
       </Contract>

The correct result should look like this:

1. George Person2 representing a person: John Person1


2. Andy Person3


3. Agnes Person4 representing a firm: VeloDrom Description


4. Michael Person5 representing a firm: VeloDrom Description

My attempt to solve the (unsuccessful):

      <xsl:template match="Contract">
        <xsl:apply-templates select="Parametr1"/>
      </xsl:template>


      <xsl:template match="Parametr1">

          <xsl:apply-templates select="Interposes/Accomplice/Person"/>

          <xsl:apply-templates select="Interposes/Representative"/>

      </xsl:template>


      <xsl:template match="Interposes/Accomplice/Person | Interposes/Representative">
          <xsl:number format="1. " count="Interposes/Accomplice/Person | Interposes/Representative"/>
        <xsl:choose>
          <xsl:when test="count(./Interposes/Representative)=0">
            <xsl:apply-templates select="Interposes/Accomplice/Person"/>
          </xsl:when>
          <xsl:when test="count(./Interposes/Representative) &gt; 0">
            <xsl:text> </xsl:text>
              <xsl:value-of select="./Name"/><xsl:text> </xsl:text>
            <xsl:value-of select="./Surname"/>
            <xsl:if test="count(../Representative) &gt; 0">
              <xsl:if test="../Accomplice/Person">
                <xsl:text>, representing a person: </xsl:text>
                <xsl:value-of select="../Accomplice/Person/Name"/><xsl:text> </xsl:text>
                   <xsl:value-of select="../Accomplice/Person/Surname"/>
                 </xsl:if>
                 <xsl:if test="../Accomplice/Firm">
                   <xsl:text>, representing a firm: </xsl:text>
                   <xsl:value-of select="../Accomplice/Firm/FirmName"/><xsl:text> </xsl:text>
                   <xsl:value-of select="../Accomplice/Firm/Description"/>
                 </xsl:if>
               </xsl:if>
             </xsl:when>
           </xsl:choose>
       </xsl:template>

How to do it correctly?