diff --git a/rivkms/Backtracking/31413.cpp b/rivkms/Backtracking/31413.cpp
new file mode 100644
index 0000000..2b6500d
--- /dev/null
+++ b/rivkms/Backtracking/31413.cpp
@@ -0,0 +1,59 @@
+// <미완>
+#include <iostream>
+#include <vector>
+#include <algorithm>
+
+using namespace std;
+int N, M, A, D;
+vector<int> vec;
+pair<int, int> compare(const pair<int, int>& p1, const pair<int, int>& p2) {
+    if (p1.second > p2.second) {
+        if (p2.first >= M) {
+            return p2;
+        }
+        return p1;
+    }
+    if (p1.second < p2.second) {
+        if (p1.first >= M) {
+            return p1;
+        }
+        return p2;
+    }
+    return p1.first > p2.first ? p1 : p2;
+}
+
+pair<int, int> dfs(bool blood, int point, int num, int n) {
+    if (n == N) {
+        return pair<int, int>(point, num);
+    }
+    if (!blood) {
+        point += vec[n];
+        pair<int, int> p1 = dfs(false, point, num, n + 1);
+        pair<int, int> p2 = dfs(true, point, num, n + 1);
+        return compare(p1, p2);
+    }
+    else {
+        point += A;
+        num += D;
+        return dfs(false, point, num, n + 1);
+    }
+}
+
+int main() {
+    int tmp;
+    cin >> N >> M;
+    for (int i = 0; i < N; i++) {
+        cin >> tmp;
+        vec.push_back(tmp);
+    }
+    cin >> A >> D;
+
+    pair<int, int> p = dfs(false, 0, 0, 0);
+    if (p.first >= M) {
+        cout << -1;
+    }
+    else {
+        cout << p.second;
+    }
+    return 0;
+}
\ No newline at end of file
diff --git a/rivkms/README.md b/rivkms/README.md
index fdba398..98fae2c 100644
--- a/rivkms/README.md
+++ b/rivkms/README.md
@@ -6,4 +6,5 @@
 | 2차시 | 2024.02.15 |  Recursion  | [하노이 탑 이동 순서](https://www.acmicpc.net/problem/11729)  | [#2](https://github.com/AlgoLeadMe/AlgoLeadMe-7/pull/8) |
 | 3차시 | 2024.02.18 |  DP  | [하노이 탑 이동 순서](https://www.acmicpc.net/problem/10844)  | [#3](https://github.com/AlgoLeadMe/AlgoLeadMe-7/pull/11) |
 | 4차시 | 2024.02.18 |  Backtracking  | [N-queen](https://www.acmicpc.net/problem/9663)  | [#4](https://github.com/AlgoLeadMe/AlgoLeadMe-7/pull/13) |
+| 5차시 | 2024.02.24 |  Backtracking  | [입대](https://www.acmicpc.net/problem/31413)  | [#5](https://github.com/AlgoLeadMe/AlgoLeadMe-7/pull/18) |
 ---