diff --git a/20/20.awk b/20/20.awk
new file mode 100644
index 0000000..fa9ae36
--- /dev/null
+++ b/20/20.awk
@@ -0,0 +1,78 @@
+BEGIN{ RS = ""; FS="" }
+
+NR==1{
+	for(i=1;i<=NF;i++){
+		en[i-1] = $i=="#" ? 1 : 0
+	}
+	RS = "\n"
+	next
+}
+
+{
+	for(i=-1;i<=NF+2;i++){
+		if(i>=1 && i<=NF)
+			inp[i,NR-1] = $i=="#" ? 1 : 0
+		else
+			inp[i,NR-1] = 0
+	}
+}
+
+function wintonum(px,py){
+	nbit = 8; num=0
+	for(j=py-1;j<=py+1;j++){
+		for(i=px-1;i<=px+1;i++){
+			b = inp[i,j]=="" ? 0 : inp[i,j]
+			num += lshift( b, nbit)
+			nbit--
+		}
+	}
+	return num
+}
+
+function wintonum2(px,py){
+	nbit = 8; num=0
+	for(j=py-1;j<=py+1;j++){
+		for(i=px-1;i<=px+1;i++){
+			b = inp[i,j]=="" ? en[0] : inp[i,j]
+			num += lshift( b, nbit)
+			nbit--
+		}
+	}
+	return num
+}
+
+END{
+	xmin=-1; xmax=NF+2
+	ymin=-1; ymax=NR+1
+
+	count = 0
+	# first pass
+	for(y=ymin; y<=ymax; y++){
+		for(x=xmin; x<=xmax; x++){
+			newinp[x,y] = en[ wintonum(x,y) ]
+			count += en[ wintonum(x,y) ]
+#			printf "%c", newinp[x,y]==1? "#" : "."
+		}
+#		print ""
+	}
+	print count
+
+	print ""
+
+	delete inp
+	# copy result
+	for(p in newinp) inp[p] = newinp[p]
+
+	# second pass
+	count = 0
+	for(y=ymin; y<=ymax; y++){
+		for(x=xmin; x<=xmax; x++){
+			wn = wintonum2(x,y)
+			count += en[ wn ]
+#			printf "%c", en[ wn ]==1 ? "#" : "."
+		}
+#		print ""
+	}
+
+	print count
+}
diff --git a/20/Makefile b/20/Makefile
new file mode 100644
index 0000000..442c528
--- /dev/null
+++ b/20/Makefile
@@ -0,0 +1,14 @@
+1t:
+	awk -f 20.awk test
+
+1i:
+	awk  -f 20.awk input
+
+2t:
+	awk  -f 20_2.awk test
+
+2i:
+	awk  -f 20_2.awk input
+
+paste:
+	xclip -sel c -o > test