diff --git a/Zadania/Z97 - suma w wierszu tablicy/index.php b/Zadania/Z97 - suma w wierszu tablicy/index.php
index f0217fd..fdc767d 100644
--- a/Zadania/Z97 - suma w wierszu tablicy/index.php	
+++ b/Zadania/Z97 - suma w wierszu tablicy/index.php	
@@ -57,6 +57,7 @@ if ($_SERVER['REQUEST_METHOD'] == 'POST') {
         (int)$nInput == $nInput && (int)$mInput == $mInput &&
         (int)$nInput > 0 && (int)$nInput <= 100 &&
         (int)$mInput > 0 && (int)$mInput <= 100;
+    $isRowNumValid = is_numeric($rowNumInput) && (int)$rowNumInput >= 0 && (int)$rowNumInput < (int)$nInput - 1;
 
     $n = (int)$nInput;
     $m = (int)$mInput;