diff --git a/examples/guessing_game.plthy b/examples/guessing_game.plthy
index 68853e6..8868e8e 100644
--- a/examples/guessing_game.plthy
+++ b/examples/guessing_game.plthy
@@ -2,7 +2,7 @@ hello|
 set do random<1;128;> -> r|
 set 0 -> guess|
 do [
-    set do input<'guess: ';> -> guess|
+    set do int<do input<'guess: ';>;> -> guess|
     do do print<'too high';> if variable guess > variable r|
     do do print<'too low';> if variable guess < variable r|
     do do print<'correct!';> if variable guess = variable r|
diff --git a/examples/pol_not_calc.plthy b/examples/pol_not_calc.plthy
index 919f85a..7570292 100644
--- a/examples/pol_not_calc.plthy
+++ b/examples/pol_not_calc.plthy
@@ -16,17 +16,48 @@ define split<1> as [
     return variable list|
 ]|
 
-define calc<1> as [
+define is_number<1> as [
+    set '0123456789' -> numbers|
+    set 0 -> i|
+    do [
+        set 0 -> j|
+        do [
+            do skip else return false if argument #1{variable i} = variable numbers{variable j}|
+            set variable j + 1 -> j|
+        ] until variable j = do len<variable numbers;>|
+        set variable i + 1 -> i|
+    ] until variable i = do len<argument #1;>|
+    return true|
+]|
+
+define calc<3> as [
+    do return argument #2 + argument #3 if argument #1 = '+'|
+    return 'error'|
+]|
+
+define unfold<1> as [
+    do return 'error' if do len<argument #1;> = 0|
+
     set {} -> middle|
     set 1 -> i|
     do [
         set variable middle + {argument #1{variable i};} -> middle|
         set variable i + 1 -> i|
     ] until variable i = do len<argument #1;> - 1|
-    return variable middle|
+
+    do return 'error' if do len<variable middle;> = 0|
+
+    do [
+        set variable middle{0} -> middle|
+        do set do int<variable middle;> -> n1 else return 'error' if do "is_number"<variable middle;>|
+    ] else set do "unfold"<variable middle;> -> n1 if do len<variable middle;> = 1|
+
+    do set do int<argument #1{do len<argument #1;>-1};> -> n2 else return 'error' if do "is_number"<argument #1{do len<argument #1;>-1};>|
+
+    return do "calc"<argument #1{0}; variable n1; variable n2;>|
 ]|
 
 set do input<':';> -> x|
 set do "split"<variable x;> -> list|
-do print<do "calc"<variable list;>;>|
+do print<do "unfold"<variable list;>;>|
 goodbye|
\ No newline at end of file
diff --git a/plthy_impl/ast_nodes.py b/plthy_impl/ast_nodes.py
index 4087961..dd56b6a 100644
--- a/plthy_impl/ast_nodes.py
+++ b/plthy_impl/ast_nodes.py
@@ -189,7 +189,7 @@ class Builtin(Command):
                 if isinstance(result, str) or isinstance(result, int) or isinstance(result, float):
                     prints.append(str(result))
                 elif isinstance(result, list):
-                    result = f"{'{'}{''.join([str(i)+";" for i in result])}{'}'}"
+                    result = f"{'{'}{''.join([str(i)+';' for i in result])}{'}'}"
                     prints.append(str(result))
                 else:
                     print(f"C003: Incorrect type {type(result)} for builtin print")