feat: move everything to single folder

cs2030s/PE1/Pair.java

@@ -0,0 +1,22 @@
+public class Pair<T, S> {
+    private T fst;
+    private S snd;
+
+    public Pair(T fst, S snd) {
+        this.fst = fst;
+        this.snd = snd;
+    }
+
+    public T getFst() {
+        return this.fst;
+    }
+
+    public S getSnd() {
+        return this.snd;
+    }
+
+    @Override
+    public String toString() {
+        return this.fst + "; " + this.snd;
+    }
+}