[c-prog] Multimap iteration

[Jos Timanta Tarigan]

Hi, 

Im currently working with multimap in C++. So for example i got a multimap like 
this:

        m.insert(pair<const char* const, int>("a", 1));
        m.insert(pair<const char* const, int>("c", 2));
        m.insert(pair<const char* const, int>("b", 3));
        m.insert(pair<const char* const, int>("b", 4));
        m.insert(pair<const char* const, int>("a", 5));
        m.insert(pair<const char* const, int>("b", 6));

and i want to loop it but without repeating the same key eg: I want to print 
average of each key and print like this

a = 3
b = 6.3
c = 2

My current solution is loop each key and find all other value with the same 
key. So its like a loop in loop. But the problem is I print a twice, b three 
times, and C once. How can I skip the repetition so it wont print the same key 
again? 

Thank you