diff --git a/license b/license
index 1a55e83..43774df 100644
--- a/license
+++ b/license
@@ -1,4 +1,4 @@
-Copyright (c) 2020 k1574
+Copyright (c) 2020 surdeus, aka Andrey Parhomenko
 
 Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
 
diff --git a/src/cmd/goblin/main.go b/src/cmd/goblin/main.go
index 0e69d9a..dd64cee 100644
--- a/src/cmd/goblin/main.go
+++ b/src/cmd/goblin/main.go
@@ -23,6 +23,7 @@ import(
 	"github.com/surdeus/goblin/src/tool/wc"
 	"github.com/surdeus/goblin/src/tool/ftest"
 	"github.com/surdeus/goblin/src/tool/grange"
+	"github.com/surdeus/goblin/src/tool/in"
 )
 
 func main() {
@@ -48,6 +49,7 @@ func main() {
 		"wc" : mtool.Tool{wc.Run, "count words, bytes, runes etc"},
 		"ftest" : mtool.Tool{ftest.Run, "filter files by specified features"},
 		"range" : mtool.Tool{grange.Run, "too lazy"},
+		"in" : mtool.Tool{in.Run, "filter strings from stdin that aren not in arguments"},
 	}
 
 	mtool.Main("goblin", tools)
diff --git a/src/tool/in/main.go b/src/tool/in/main.go
new file mode 100644
index 0000000..c1a3fdd
--- /dev/null
+++ b/src/tool/in/main.go
@@ -0,0 +1,74 @@
+package in
+
+import (
+	"os"
+	"io"
+	"bufio"
+	"fmt"
+	"flag"
+)
+
+func Run(args []string) {
+	var (
+		print bool
+		not bool
+	)
+	arg0 := args[0]
+	args = args[1:]
+	flagSet := flag.NewFlagSet(arg0, flag.ExitOnError)
+	flagSet.BoolVar(&print, "p", false, "print matching lines")
+	flagSet.BoolVar(&not, "n", false, "find not matching lines")
+	flagSet.Usage = func() {
+		fmt.Fprintf(os.Stderr, "usage: %s <str1> [str2, ...str3]\n", arg0)
+		flagSet.PrintDefaults()
+		os.Exit(1)
+	}
+
+	flagSet.Parse(args)
+	args = flagSet.Args()
+
+	if len(args) == 0 {
+		flagSet.Usage()
+	}
+
+	mp := make(map[string] int)
+	for _, v := range args {
+		mp[v] = 0
+	}
+
+	status := 1
+	r := bufio.NewReader(os.Stdin)
+
+	if not {
+		status = 0
+	}
+	for {
+		l, err := r.ReadString('\n')
+		if err == io.EOF {
+			break
+		}
+
+		if len(l) != 0 && l[len(l)-1] == '\n' {
+			l = l[:len(l)-1]
+		}
+
+		_, ok := mp[l]
+		if not {
+			if ok {
+				status = 1
+				ok = false
+			} else {
+				ok = true
+			}
+		} else {
+			if ok {
+				status = 0
+			}
+		}
+
+		if print && ok {
+			fmt.Println(l)
+		}
+	}
+	os.Exit(status)
+}