C++: Given three strings on separate lines, insert the contents of the second string in the first string right before the third string. Then, output the result

Ex: If the input is:
FuzzyBear

Wuzzy

Be

the output is:
FuzzyWuzzyBear

Note: Using a pre-defined string function, the solution can be just one line of code.

(I tried using strVar. insert(partStr, str2) but was unsuccessful. I don’t know where I’m messing up. Thank you for your help. I’ve been trying to alter this code for a while now)