diff --git a/src/week1/BOJ3986/BOJ3986_V1.cpp b/src/week1/BOJ3986/BOJ3986_V1.cpp
new file mode 100644
index 0000000..b50bdb5
--- /dev/null
+++ b/src/week1/BOJ3986/BOJ3986_V1.cpp
@@ -0,0 +1,65 @@
+#include<bits/stdc++.h>
+using namespace std;
+vector<int> A;
+vector<int> B;
+int count_A;
+int count_B;
+vector<string> input_str;
+int result_cnt;
+void clear_input() {
+    count_A = 0;
+    count_B = 0;
+    A.clear();
+    B.clear();
+}
+
+int check(const vector<int>& vec) {
+    for (int j=0; j<vec.size()/2; j++) {
+        int dist = vec[2*j+1] - vec[2*j];
+        if (dist % 2 == 0) {
+            return 0;
+        }
+    }
+    return 1;
+}
+int main() {
+
+    int n;
+    cin >> n;
+
+    for (int i=0; i<n; i++) {
+        string temp;
+        cin >> temp;
+        input_str.push_back(temp);
+    }
+
+    for (int i=0; i<n; i++) {
+        for (int j=0; j<input_str[i].size(); j++) {
+            if (input_str[i][j] == 'A') {
+                A.push_back(j);
+                count_A++;
+            }
+            if (input_str[i][j] == 'B') {
+                B.push_back(j);
+                count_B++;
+            }
+        }
+        if (count_A %2 == 1 || count_B %2 == 1) {
+            clear_input();
+            continue;
+        }
+
+        int flag_A = check(A);
+        int flag_B = check(B);
+
+
+        if (flag_A && flag_B)
+            result_cnt++;
+
+        clear_input();
+    }
+
+    cout<< result_cnt << "\n";
+
+
+}
\ No newline at end of file
diff --git a/src/week1/BOJ3986/BOJ3986_V2.cpp b/src/week1/BOJ3986/BOJ3986_V2.cpp
new file mode 100644
index 0000000..22c4e58
--- /dev/null
+++ b/src/week1/BOJ3986/BOJ3986_V2.cpp
@@ -0,0 +1,31 @@
+#include <bits/stdc++.h>
+using namespace std;
+int n;
+int cnt;
+
+int main() {
+
+    cin >> n;
+
+    for (int i = 1; i <= n; i++) {
+        stack<char> stk;
+        string s;
+        cin >> s;
+        for (int j = 0; j < s.length(); j++) {
+            if (stk.size() != 0 && stk.top() == s[j]) {
+                stk.pop();
+            } else {
+                stk.push(s[j]);
+            }
+        }
+
+        if (stk.size() == 0) {
+            cnt++;
+        }
+
+    }
+
+    cout << cnt << "\n";
+
+    return 0;
+}