docs: 1977번 문제를 통한 패치 테스트

Author: isho-0

src/problem_includes.h

@@ -8,6 +8,7 @@
 #include "problems/problem_1001.h"
 #include "problems/problem_10950.h"
 #include "problems/problem_10952.h"
+#include "problems/problem_1977.h"
 #include "problems/problem_2438.h"
 #include "problems/problem_2439.h"
 #include "problems/problem_2440.h"

src/problem_manager.cc

@@ -7,6 +7,7 @@ ProblemManager::ProblemManager() {
   // 문제 등록
   problems_[1000] = solve_problem_1000;
   problems_[1001] = solve_problem_1001;
+  problems_[1977] = solve_problem_1977;
   problems_[2438] = solve_problem_2438;
   problems_[2439] = solve_problem_2439;
   problems_[2440] = solve_problem_2440;