diff --git a/src/week6/BOJ1561/BOJ1561_V1.cpp b/src/week6/BOJ1561/BOJ1561_V1.cpp
new file mode 100644
index 0000000..179a004
--- /dev/null
+++ b/src/week6/BOJ1561/BOJ1561_V1.cpp
@@ -0,0 +1,65 @@
+#include <bits/stdc++.h>
+using namespace std;
+long long int N,M;
+vector<int> available;
+bool check(long long int num) {
+    long long int cnt = M;
+    for (int i=0; i<M; i++) {
+        cnt += (num / available[i]);
+    }
+
+    return cnt >= N;
+}
+int main() {
+
+    ios_base::sync_with_stdio(false);
+    cin.tie(nullptr);
+    cout.tie(nullptr);
+
+    cin >> N >> M;
+
+
+
+    for (int i=0; i<M; i++) {
+        int num;
+        cin >> num;
+        available.push_back(num);
+    }
+
+    if (N <= M) {
+        cout << N << '\n';
+        return 0;
+    }
+    long long int mid,low=0,high=N*30, time;
+
+    while(low <= high) {
+        mid = (low + high) / 2;
+        if (check(mid)) {
+            time = mid;
+            high = mid - 1;
+        } else {
+            low = mid + 1;
+        }
+    }
+
+    long long finishTime = time;
+    long long before = M;
+
+    for (int i = 0; i < M; i++) {
+        before += (finishTime - 1) / available[i];
+    }
+
+    long long int cnt = N-before;
+
+    for (int i=0; i<M; i++) {
+        if (finishTime % available[i] == 0) {
+            cnt--;
+            if (cnt == 0) {
+                cout << i + 1;
+                return 0;
+            }
+        }
+    }
+
+    return 0;
+}