Compilation issue with subscript operator overloading when another conversion operator is added [duplicate]

The following piece of code compiles fine

#include <iostream>
#include <map>
#include <memory>

using namespace std;

class child {
    public:
    child(std::string name,uint32_t age) : name(name),age(age){
    }
    std::string name;
    uint32_t age;
};

class parent {
    public:
    uint32_t age;
    parent(std::string name){
        age = 10;
    }
    std::map<uint32_t, std::shared_ptr<child>> child_by_age;
    std::map<std::string, std::shared_ptr<child>> child_by_name;

    child& operator[](const uint32_t& num){
        return *(child_by_age[num]);
    }

    child& operator[](const std::string& n){
        return *(child_by_name[n]);
    }

    void addChild(const child& ch){
        auto ch_obj = std::make_shared<child>(ch);
        child_by_age.emplace(ch.age, ch_obj);
        child_by_name.emplace(ch.name, ch_obj);
    }
};

class top {
    public:
    parent p1;
    top():p1("p1"){
        p1.addChild(child("c0",0));
        p1.addChild(child("c1",1));
    }
    void run(){
        p1["c0"].name = "name";
        p1[0].name = "name1";
    }
};

int main(){
    top t;
    t.run();
    return 0;
}

But the moment I add following conversion operator

   operator uint32_t() const{
        return age;
    }

I am getting the following error

operator_overload.cpp: In member function ‘void top::run()’: operator_overload.cpp:50:11: error: ambiguous overload for ‘operator[]’ (operand types are ‘parent’ and ‘const char [3]’) p1["c0"].name = "name"; ^ operator_overload.cpp:50:11: note: candidate: operator[](long int, const char*) operator_overload.cpp:28:12: note: candidate: child& parent::operator[](const string&) child& operator[](const std::string& n){ ^~~~~~~~

I am not sure to understand why the compiler complains on subscript operator when I add conversion operator