diff --git a/day19/sol.tcl b/day19/sol.tcl
index 23eb66e..608c28f 100755
--- a/day19/sol.tcl
+++ b/day19/sol.tcl
@@ -45,15 +45,106 @@ proc filter {flows value} {
     return $f
 }
 
-
-set flows [read-workflows stdin]
-set values [read-values stdin]
-puts $flows
-puts $values
-foreach v $values {
-    set f [filter $flows $v]
-    set score [ladd [lextract $v 2 1]]
-    puts "$v : $f : $score"
-    if {$f eq "A"} { incr t $score }
+proc solve input {
+    set flows [read-workflows stdin]
+    set values [read-values stdin]
+    puts $flows
+    puts $values
+    foreach v $values {
+        set f [filter $flows $v]
+        set score [ladd [lextract $v 2 1]]
+        puts "$v : $f : $score"
+        if {$f eq "A"} { incr t $score }
+    }
+    puts "$t"
 }
-puts "$t"
+
+proc unfilter flows {
+    lappend state(in) [dict create x {1 4000} m {1 4000} a {1 4000} s {1 4000}]
+    #set state(in) {
+    #    {x {787 787} m {2655 2655} a {1222 1222} s {2876 2876}}
+    #    {x {1679 1679} m {44 44} a {2067 2067} s {496 496}}
+    #    {x {2036 2036} m {264 264} a {79 79} s {2244 2244}}
+    #    {x {2461 2461} m {1339 1339} a {466 466} s {291 291}}
+    #    {x {2127 2127} m {1623 1623} a {2188 2188} s {1013 1013}}
+    #}
+    #set flows [dict map {k v} $flows {lmap }
+    set done 0
+    while {!$done} {
+        puts [array get state]
+        # break if everything is in the accept or reject state
+        set done 1
+        foreach {f ranges} [array get state] {
+            if {$f eq "A" || $f eq "R"} continue
+            set done 0
+            unset state($f)
+            foreach range $ranges {
+                set rules [dict get $flows $f]
+                foreach {cond dest} $rules {
+                    if {$cond eq "default"} {
+                        lappend state($dest) $range
+                        break
+                    }
+                    if {[string first < $cond] >= 0} {
+                        lassign [split $cond <] var cutoff
+                        set key [trim $var "$"] ;# TODO
+                        lassign [dict get $range $key] min max
+                        if {$cutoff > $max} {
+                            # entire range already lower than required
+                            lappend state($dest) $range
+                            break
+                        }
+                        if {$min >= $cutoff} {
+                            # entire range above required value
+                            continue
+                        }
+                        # split range
+                        lappend state($dest) [dict replace $range $key [list $min [expr {$cutoff-1}]]]
+                        dict set range $key [list $cutoff $max]
+                        continue
+                    }
+                    if {[string first > $cond] >= 0} {
+                        lassign [split $cond >] var cutoff
+                        set key [trim $var "$"]
+                        lassign [dict get $range $key] min max
+                        if {$cutoff < $min} {
+                            # entire range already greater than required
+                            lappend state($dest) $range
+                            break
+                        }
+                        if {$max <= $cutoff} {
+                            # entire range below required value
+                            continue
+                        }
+                        # split range
+                        lappend state($dest) [dict replace $range $key [list [expr {$cutoff+1}] $max]]
+                        dict set range $key [list $min $cutoff]
+                        continue
+                    }
+                    error "unhandled rule $cond:$dest"
+                }
+            }
+        }
+    }
+    set t 0
+    foreach r $state(A) {
+        set p 1
+        foreach {min max} [join [dict values $r]] {
+            if {$min > $max} {
+                error "invalid range: $min $max"
+            }
+            set p [expr {$p * ($max - $min + 1)}]
+        }
+        incr t $p
+        puts "A: $r = $p"
+    }
+    puts "$t"
+}
+
+proc solve2 input {
+    set flows [read-workflows stdin]
+    #set values [read-values stdin]
+    unfilter $flows
+}
+
+solve2 stdin