diff --git a/p11.dyalog b/p11.dyalog
new file mode 100644
index 0000000..631b02c
--- /dev/null
+++ b/p11.dyalog
@@ -0,0 +1,5 @@
+⎕IO←1
+p←⍎⊃⊃⎕NGET'p11.txt'1
+g←{r y←10 0+⍵ ⋄ ¯5+10|⌊100÷⍨r×p+y×r}¨⍳300 300 ⍝ grid
+¯1+⊃⍸{⍵=⌈/,⍵}{+/,⍵}⌺3 3⊢g ⍝ part 1
+1↓{(⊃⍒⍵)⌷⍵}↑1{0>m←⌈/,t←{+/,⍵}⌺⍺ ⍺⊢g:⍵ ⋄ (⍺+1)∇⍵,⊂m,((⊃⍸m=t)-⌊0.5×⍺-1),⍺}⍬ ⍝ part 2
diff --git a/p11.txt b/p11.txt
new file mode 100644
index 0000000..9d3c219
--- /dev/null
+++ b/p11.txt
@@ -0,0 +1 @@
+5468