How to find if a given key exists in a C std map

Question

I'm trying to check if a given key is in a map and somewhat can't do it:

typedef map<string,string>::iterator mi;
map<string, string> m;
m.insert(make_pair("f","++--"));
pair<mi,mi> p = m.equal_range("f");//I'm not sure if equal_range does what I want
cout << p.first;//I'm getting error here