FOR C++
TO INCLUDE ALL THE LIBRARY FILES USE #include bits/stdc++.h . THIS HEADER FILES INCLUDES ALL THE LIBRARY FILES REQUIRED FOR A TYPICAL COMPETITIVE PROGRAMMING ENVIRONMENT LIKE ALGORITHMS, MULTISET, SET ETC.
IN YOUR CASE IT IS SUFFICE TO INCLUDE THIS HEADER FILE OR YOU CAN JUST #include string.
Dont forget to put use namespace std in your file.