diff --git a/.travis.yml b/.travis.yml
index 455f3c0..45c29f6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,6 @@
 language: clojure
-lein: lein2
-script: lein2 midje :config .midje-grading-config.clj
+lein: lein
+script: lein midje :config .midje-grading-config.clj
 jdk:
   - openjdk7
 notifications:
diff --git a/src/one_function_to_rule_them_all.clj b/src/one_function_to_rule_them_all.clj
index 6844d99..b77f095 100644
--- a/src/one_function_to_rule_them_all.clj
+++ b/src/one_function_to_rule_them_all.clj
@@ -1,43 +1,65 @@
 (ns one-function-to-rule-them-all)
 
 (defn concat-elements [a-seq]
-  :-)
+  (reduce concat () a-seq))
 
 (defn str-cat [a-seq]
-  :-)
+  (if (empty? a-seq)
+    ""
+    (reduce (fn [str1 str2] (str str1 " " str2)) a-seq)))
 
 (defn my-interpose [x a-seq]
-  [:-])
+  (if (empty? a-seq)
+    []
+    (reduce (fn [vec elem] (conj vec x elem)) [(first a-seq)] (rest a-seq))))
 
 (defn my-count [a-seq]
-  :-)
+  (reduce (fn [count _] (inc count)) 0 a-seq))
 
 (defn my-reverse [a-seq]
-  [:-])
+  (reduce conj () a-seq))
 
 (defn min-max-element [a-seq]
-  [:-])
+  (let [first (first a-seq)
+        min-max (fn [[mini maxi] x] [(min mini x) (max maxi x)])]
+    (reduce min-max [first first] (rest a-seq))))
 
 (defn insert [sorted-seq n]
-  [:-])
+  (loop [result []
+        remaining sorted-seq]
+    (cond
+      (empty? remaining) (concat result [n])
+      (< n (first remaining)) (concat result (cons n remaining))
+      :else (recur (conj result (first remaining)) (rest remaining)))))
 
 (defn insertion-sort [a-seq]
-  [:-])
+  (reduce insert [] a-seq))
 
 (defn parity [a-seq]
-  [:-])
+  (let [toggle (fn [a-set elem]
+                (if (contains? a-set elem)
+  	              (disj a-set elem)
+  	              (conj a-set elem)))]
+    (reduce toggle #{} a-seq)))
 
-(defn minus [x]
-  :-)
+(defn minus 
+  ([x] (- x))
+  ([x y] (- x y)))
 
-(defn count-params [x]
-  :-)
+(defn count-params [& args]
+  (count args))
 
-(defn my-* [x]
-  :-)
+(defn my-*
+  ([] 1)
+  ([x] x)
+  ([x y] (* x y))
+  ([x y & more] (reduce * (* x y) more)))
 
-(defn pred-and [x]
-  (fn [x] :-))
+(defn pred-and
+  ([] (fn [_] true))
+  ([p?] p?)
+  ([p1? p2?] (fn [x] (and (p1? x) (p2? x))))
+  ([p1? p2? & more] (reduce pred-and (pred-and p1? p2?) more)))
 
 (defn my-map [f a-seq]
-  [:-])
\ No newline at end of file
+  )