diff --git a/.gitignore b/.gitignore
index 4fa74d7..7ff8f11 100644
--- a/.gitignore
+++ b/.gitignore
@@ -14,4 +14,6 @@
 # Project-local glide cache, RE: https://github.com/Masterminds/glide/issues/736
 .glide/
 
-01dec/01dec
+??dec/??dec
+*~
+*.swp
diff --git a/02dec/checksum.go b/02dec/checksum.go
new file mode 100644
index 0000000..62a54cd
--- /dev/null
+++ b/02dec/checksum.go
@@ -0,0 +1,33 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"math"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func main() {
+	var sum int
+	in := bufio.NewScanner(os.Stdin)
+	for in.Scan() {
+		sum += diff(in.Text())
+	}
+	fmt.Println(sum)
+}
+
+func diff(l string) int {
+	min, max := math.MaxInt64, 0
+	for _, s := range strings.Split(l, "\t") {
+		i, _ := strconv.Atoi(s)
+		if min >= i {
+			min = i
+		}
+		if max <= i {
+			max = i
+		}
+	}
+	return max - min
+}
diff --git a/02dec/input b/02dec/input
new file mode 100644
index 0000000..04bed48
--- /dev/null
+++ b/02dec/input
@@ -0,0 +1,16 @@
+3093	749	3469	142	2049	3537	1596	3035	2424	3982	3290	125	249	131	118	3138
+141	677	2705	2404	2887	2860	1123	2714	117	1157	2607	1800	153	130	1794	3272
+182	93	2180	114	103	1017	95	580	2179	2470	2487	2806	1574	1325	1898	1706
+3753	233	3961	3747	3479	3597	1303	2612	4043	1815	3318	737	197	3943	239	254
+113	147	961	157	3514	3045	1270	3528	1369	3377	492	156	1410	3251	1839	1249
+3948	3651	888	3631	253	220	4266	1284	3595	237	2138	3799	2319	254	267	1182
+399	446	795	653	154	762	140	487	750	457	730	150	175	841	323	492
+999	979	103	99	1544	1404	100	1615	840	92	1552	1665	1686	76	113	1700
+4049	182	3583	1712	200	3326	3944	715	213	1855	2990	3621	2560	842	249	2082
+2610	4749	2723	2915	2189	3911	124	164	1895	3095	3992	134	127	4229	3453	4428
+105	692	101	150	193	755	84	185	622	851	706	251	86	408	774	831
+238	217	224	1409	1850	2604	363	265	596	2933	2641	2277	803	2557	1399	237
+304	247	192	4369	997	5750	85	1248	4718	3888	5228	5116	5880	5348	6052	245
+238	373	228	395	86	59	289	87	437	384	233	79	470	403	441	352
+151	3473	1435	87	1517	1480	140	2353	1293	118	163	3321	2537	3061	1532	3402
+127	375	330	257	220	295	145	335	304	165	151	141	289	256	195	272