fix keep image number

main.go

@@ -114,6 +114,7 @@ func main() {
 	}
 
 	iarr := ImageArr{}
+	keepNum := runFlag.KeepNum
 	for _, v := range imgs.ImageDetails {
 		excludeFlag := false
 		if len(runFlag.ExcludeTag) > 0 {
@@ -123,6 +124,7 @@ func main() {
 					if *v2 == e {
 						f = true
 						excludeFlag = true
+						keepNum--
 						break
 					}
 				}
@@ -135,8 +137,11 @@ func main() {
 			iarr = append(iarr, v)
 		}
 	}
+	if keepNum < 0 {
+		keepNum = 0
+	}
 	sort.Stable(iarr)
-	iarr = iarr[runFlag.KeepNum:]
+	iarr = iarr[keepNum:]
 	if len(iarr) == 0 {
 		fmt.Println("no delete image")
 		return