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diff --git a/challenge-158/cheok-yin-fung/dart/ch-1.dart b/challenge-158/cheok-yin-fung/dart/ch-1.dart
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+++ b/challenge-158/cheok-yin-fung/dart/ch-1.dart
@@ -0,0 +1,27 @@
+// The Weekly Challenge 158
+// Task 1 Additive Primes
+// Usage: $ dart ch-1.dart [upper bound, not larger than 1000]
+import 'dart:math';
+
+void main(List<String> args) {
+  int arg = args.length > 0 && int.parse(args[0]) <= 1000 ? 
+                int.parse(args[0]) : 100;
+  var small_primes = <int>[2, 3, 5, 7, 11, 13, 17]; // less than 9+9 = 18
+  if (arg > 100) small_primes.addAll([19, 23, 29, 31]);
+  print("Upper Bound: " + arg.toString());
+  var prime = <int>[2];
+  LOOP: for (int i = 3; i <= arg; i+=2) {
+    for (int k = 0; k < prime.length && prime[k] <= sqrt(i); k++) {
+      if (i % prime[k] == 0) continue LOOP;
+    }
+    prime.add(i);
+  }
+
+  for (int j = 0; j < prime.length; j++) {
+    int sum = 0;
+    var list = prime[j].toString().split("");
+    list.forEach( (e) => sum += int.parse(e) );
+    var found = small_primes.any( (p) => p == sum );
+    if (found) print(prime[j]);
+  }
+}
diff --git a/challenge-158/cheok-yin-fung/dart/ch-2.dart b/challenge-158/cheok-yin-fung/dart/ch-2.dart
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+++ b/challenge-158/cheok-yin-fung/dart/ch-2.dart
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+// The Weekly Challenge 158
+// Task 2 Cuban Primes
+// Usage: $ dart ch-2.dart [Upper bound]
+// using Wheel Factorization (though seems that it is better for sieve...)
+// check result with OEIS:A002407
+import 'dart:math';
+
+void main(List<String> args) {
+  int arg = args.length > 0 ? int.parse(args[0]) : 1000;
+  List rp_to_30 = <int>[1, 7, 11, 13, 17, 19, 23, 29]; 
+  int y = 3;
+  int pp = 37;
+  if (7 <= arg) print(7);
+  if (19 <= arg) print(19);
+  List spokes = <int>[];
+  for (int i = 1; i < rp_to_30.length; i++)
+    spokes.add( rp_to_30[i] );  // skip 1
+  while (pp <= arg) {
+    if (pp % 5 == 0) continue;  // pp must be coprime to 2 and 3.
+    if (spokes.last <= sqrt(pp)) {
+      for (int k=1; k*30 <= sqrt(pp); k++)
+        rp_to_30.forEach( (e) => spokes.add(e+k*30) );
+    }
+    y++;
+    if (spokes.any( (d) => pp % d == 0 )) {
+      pp = 3*y*y + 3*y + 1;
+      continue;
+    } else {
+      print(pp.toString());
+      pp = 3*y*y + 3*y + 1;
+    }
+  }
+}