diff --git a/dayfour.go b/dayfour.go
new file mode 100644
index 0000000..4f14a9d
--- /dev/null
+++ b/dayfour.go
@@ -0,0 +1,21 @@
+package main
+
+func incrementIfEncapsulated(pair [2][2]int, solution *int) {
+	if isEncapsulated(pair[0], pair[1]) {
+		*solution++
+	}
+}
+
+func isEncapsulated(first [2]int, second [2]int) bool {
+	return first[0] <= second[0] && first[1] >= second[1] || second[0] <= first[0] && second[1] >= first[1]
+}
+
+func dayFour(input [][2][2]int) int {
+	solution := 0
+
+	for _, pair := range input {
+		incrementIfEncapsulated(pair, &solution)
+	}
+
+	return solution
+}
diff --git a/main.go b/main.go
index ee95aa8..9cae855 100644
--- a/main.go
+++ b/main.go
@@ -70,5 +70,20 @@ func main() {
 	`)
 
 	fmt.Println(dayThreeResult)
-	// printRunes()
+
+
+	/** DAY FOUR */
+	fmt.Println("\nDAY FOUR")
+
+	dayFourInput := [][2][2]int{
+		{{2, 4}, {6, 8}},
+		{{2, 3}, {4, 5}},
+		{{5, 7}, {7, 9}},
+		{{2, 8}, {3, 7}},
+		{{6, 6}, {4, 6}},
+		{{2, 6}, {4, 8}},
+	}
+
+	var dayFourResult = dayFour(dayFourInput)
+	fmt.Println(dayFourResult)
 }