diff --git a/ch1/1_4.go b/ch1/1_4.go
new file mode 100644
index 0000000..c4acd56
--- /dev/null
+++ b/ch1/1_4.go
@@ -0,0 +1,51 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"os"
+	"strings"
+)
+
+func main() {
+	counts := make(map[string][]string)
+	file := os.Args[1:]
+	if len(file) == 0 {
+		countLines(os.Stdin, counts)
+	} else {
+		for _, i := range file {
+			f, err := os.Open(i)
+			if err != nil {
+				log.Print(err)
+			}
+			countLines(f, counts)
+			f.Close()
+		}
+	}
+	for lines, n := range counts {
+		if len(n) > 1 {
+			fmt.Printf("%v\t\"%s\"\n", n, strings.Trim(lines, " "))
+		}
+	}
+}
+
+func contains(slice []string, file string) bool {
+	for _, i := range slice {
+		if i == file {
+			return true
+		}
+	}
+	return false
+}
+
+func countLines(f *os.File, counts map[string][]string) {
+	input := bufio.NewScanner(f)
+	for input.Scan() {
+		cur := counts[input.Text()]
+		if !contains(cur, f.Name()) {
+			cur = append(cur, f.Name())
+			counts[input.Text()] = cur
+		}
+	}
+}