diff --git a/day13/dayThirteen.go b/day13/dayThirteen.go
index de9afc4..6ed2688 100644
--- a/day13/dayThirteen.go
+++ b/day13/dayThirteen.go
@@ -8,7 +8,7 @@ import (
 )
 
 func Run() int {
-	filename := "day13/input"
+	filename := "day13/example"
 	fmt.Println("hello day 13.", filename)
 	bytes, err := os.ReadFile(filename)
 	if err != nil {
@@ -42,7 +42,7 @@ func Calc(field Field) int {
 					isMirrored := symb == mirroredSymb
 					if !isMirrored {
 						// log.Printf("found not mirrored : %s != %s\n", string(symb), string(mirroredSymb))
-						horizontalMirrorUnderCheck.FailedLineChecks[rowNum] = struct{}{}
+						horizontalMirrorUnderCheck.FailedLineChecks[rowNum] += 1
 					}
 				}
 			}
@@ -59,8 +59,9 @@ func Calc(field Field) int {
 
 	rowsAboveHorizontals := 0
 	for _, mirr := range horizontals {
-		fmt.Println(mirr.String())
+		fmt.Println("horizontal: ", mirr.String())
 		if mirr.isFullMirror() {
+			log.Printf(">> found perfect Horizontal %+v\n", mirr)
 			rowsAboveHorizontals += (mirr.Smaller + 1)
 		}
 	}
@@ -77,7 +78,7 @@ func Calc(field Field) int {
 					isMirrored := symb == mirroredSymb
 					if !isMirrored {
 						// log.Printf("found not mirrored : %s != %s\n", string(symb), string(mirroredSymb))
-						verticalMirrorUnderCheck.FailedLineChecks[rowNum] = struct{}{}
+						verticalMirrorUnderCheck.FailedLineChecks[rowNum] += 1
 					}
 				}
 			}
@@ -93,8 +94,9 @@ func Calc(field Field) int {
 	}
 	colsToLeftOfHorizontals := 0
 	for _, mirr := range verticals {
-		fmt.Println(mirr.String())
+		fmt.Println("vertical: ", mirr.String())
 		if mirr.isFullMirror() {
+			log.Printf(">> found perfect Vertical %+v\n", mirr)
 			colsToLeftOfHorizontals += (mirr.Smaller + 1)
 		}
 	}
@@ -146,7 +148,7 @@ func (f *Field) initMirrors() (vertical []Mirror, horizontal []Mirror) {
 			Smaller:              rowNum,
 			Bigger:               rowNum + 1,
 			SuccessfulLineChecks: make(map[int]any),
-			FailedLineChecks:     make(map[int]any),
+			FailedLineChecks:     make(map[int]int),
 			MaxDistToCheck:       maxDist,
 		}
 	}
@@ -157,7 +159,7 @@ func (f *Field) initMirrors() (vertical []Mirror, horizontal []Mirror) {
 			Smaller:              colNum,
 			Bigger:               colNum + 1,
 			SuccessfulLineChecks: make(map[int]any),
-			FailedLineChecks:     make(map[int]any),
+			FailedLineChecks:     make(map[int]int),
 			MaxDistToCheck:       min(colNum, maxDist),
 		}
 	}
@@ -172,24 +174,34 @@ type Mirror struct {
 	// i.e if mirror between 0 and 1 - only rows 0 & 1 have to be checked, row 2 is 'mirrored' outside of the field and 'ok'
 	// value 0 means one step from 'mirror' so rows 0 and 1
 	SuccessfulLineChecks map[int]any
-	FailedLineChecks     map[int]any
+	FailedLineChecks     map[int]int // from line num, to amount of errors in that line
 }
 
 func (m *Mirror)isFullMirror() bool {
-	return len(m.FailedLineChecks) == 0
+	correctFailedLinesCount := len(m.FailedLineChecks) == 2
+	if correctFailedLinesCount {
+		for failedLine, failedSymbols := range m.FailedLineChecks {
+			reflectedLine, _ := m.reflectCoord(failedLine)
+			doublyReflected, _ := m.reflectCoord(reflectedLine)
+			log.Printf(">>>> checking failed line %d, reflected is %d; doubly %d. amount failed is %d\n", failedLine, reflectedLine, doublyReflected, failedSymbols)
+			if failedSymbols == 1 && (doublyReflected == failedLine) {
+				return true
+			}
+		}
+	}
+	return false
 }
 
 func (m *Mirror)String() string {
-	return fmt.Sprintf("Mirror between %d and %d. successful lines: %+v ; failed lines: %+v. Max check dist: %d\n",
-		m.Smaller, m.Bigger, m.SuccessfulLineChecks, m.FailedLineChecks, m.MaxDistToCheck)
+	return fmt.Sprintf("Mirror (full %t) between %d and %d. successful lines: %+v ; failed lines: %+v. Max check dist: %d\n",
+		m.isFullMirror(), m.Smaller, m.Bigger, m.SuccessfulLineChecks, m.FailedLineChecks, m.MaxDistToCheck)
 }
 
 func (m *Mirror) reflectCoord(coord int) (reflected int, shouldCheck bool) {
 	dist := m.Smaller - coord
 
-	_, distFailed := m.FailedLineChecks[dist]
 	_, distConfirmed := m.SuccessfulLineChecks[dist]
-	if distFailed || distConfirmed {
+	if distConfirmed {
 		return 0, false // either line already fully confirmed, or failed. no need for additional checks
 	}