I have used enum in my code and it is crashing [closed]

Question

I am using enum in the below code and using operator overloading but it is crashing. Could anyone explain why?

#include<iostream>
using namespace std;

enum E{M, T= 3, W, Th, F, Sa, Su};

E operator+(const E &a, const E &b){
    unsigned int ea = a, eb = b;
    unsigned int ec = (a+b)%7;
    return E(ec);

}
int main(){
    E a = M, b = F;
    cout<<a<<endl;
    cout<<b<<endl;
    E day = a+b;
    //cout<<int(day)<<endl;

return 0;
}