stack_test.cpp

#include <iostream>
#include <string>
#include <stack>

int main() {
    std::string input, expected;
    std::stack<char> stack;
    std::cin >> input >> expected;
    size_t iex = 0;
    for(size_t i = 0; i < input.length(); i++) {
        stack.push(input[i]);
        while(!stack.empty() && stack.top() == expected[iex]) {
            stack.pop();
            iex++;
        }
    }
    std::cout << (iex == expected.length() ? "YES\n" : "NO\n");
}