[PF-2266] Add support for c++20 and c17

stub.c17

@@ -0,0 +1,17 @@
+#include <stdio.h>
+
+int main()
+{
+    // Declare the variable
+    int a;
+
+    // Read the variable from STDIN
+    scanf("%d", &a);
+
+    // Output the variable to STDOUT
+    printf("%d", a);
+
+    // Note that you need to explicitly return 0 in main() function,
+    // otherwise your solution won't get accepted
+    return 0;
+}

stub.cpp20

@@ -0,0 +1,20 @@
+#include <cstdio>
+#include <iostream>
+#include <algorithm>
+#include <cmath>
+#include <vector>
+
+using namespace std;
+
+int main() {
+  // Declare the variable
+  int a;
+
+  // Read the variable from STDIN
+  cin >> a;
+
+  // Output the variable to STDOUT
+  cout << a;
+
+  return 0;
+}