#includeThis code creates a deque with three elements, adds a fourth element to the back, prints the last element, removes the last element, and prints the new last element. The deque package library is part of the C++ Standard Library. The deque container is useful when you need to efficiently add or remove elements from both ends of a sequence. It can be used in many algorithms where insertion and deletion are required, such as breadth-first search.#include int main() { std::deque dq = { 1, 2, 3 }; dq.push_back(4); std::cout << "Last element: " << dq.back() << '\n'; dq.pop_back(); std::cout << "New last element: " << dq.back() << '\n'; return 0; }