Map in C++ give the key and get the string

I have created a map like this : std::map<int, std::string> mapID;

INPUT: mapID[1] = "string!";

and I want to print element with the key is the 1. For example

cout << "The string is : " << mapID.at(1)->second << endl;

OR

cout << "The string is : " << mapID.find(1)->second << endl;

But I have the error

error: no matching function for call to ‘std::map >::at(std::string&)’