How to use Boost::Variant inside a structure?

ValueType is a boost variant. I am using this as a member of struct1. I want to write + operator overloading for struct1.

1. Currently I got an error in the below code. Please help me to solve this.

   using ValueType = boost::variant;

   struct struct1 { ValueType value; int length;

   struct1 &operator+(const struct1 &right)
   {
       length = length + right.length;
       value = value + right.value; // ------> error
       return *this;
   }
   

   };

2. Can I use template structure here? If yes, please add the code with operator overloading.