diff --git a/01xxx/01173.cpp b/01xxx/01173.cpp
new file mode 100644
index 00000000..8270d5aa
--- /dev/null
+++ b/01xxx/01173.cpp
@@ -0,0 +1,28 @@
+#include <iostream>
+using namespace std;
+
+int solve(void) {
+  int N, m, M, T, R; cin >> N >> m >> M >> T >> R;
+  if (m + T > M) return -1;
+
+  int ans = 0, cur = m;
+  while (N > 0) {
+    if (cur + T <= M) {
+      cur += T;
+      N--;
+    } else {
+      cur -= R;
+      if (cur < m) cur = m;
+    }
+    ans++;
+  }
+  return ans;
+}
+
+int main(void) {
+  ios::sync_with_stdio(false);
+  cin.tie(nullptr); cout.tie(nullptr);
+
+  cout << solve();
+  return 0;
+}
\ No newline at end of file