diff --git a/QUSTOJ/1870.cpp b/QUSTOJ/1870.cpp
new file mode 100644
index 0000000..d97c744
--- /dev/null
+++ b/QUSTOJ/1870.cpp
@@ -0,0 +1,22 @@
+#include <iostream>
+using namespace std;
+
+void act(int n,char a,char b,char c)
+{
+    if(n==1)
+        cout<<a<<"---->"<<c<<endl;
+    else
+    {
+        act(n-1,a,c,b);
+        cout<<a<<"---->"<<c<<endl;
+        act(n-1,b,a,c);
+    }
+}
+
+int main()
+{
+    int n;
+    cin>>n;
+    act(n,'A','B','C');
+    return 0;
+}