diff --git a/ex1.php b/ex1.php
new file mode 100644
index 0000000..8305079
--- /dev/null
+++ b/ex1.php
@@ -0,0 +1,35 @@
+<?php
+
+//Shlykova Ksenia
+
+$cardNumber = readline("cardNumber = ");
+
+$number = str_replace(' ', '', $cardNumber);
+$number = str_replace('-', '', $number);
+$number = (int) $number;
+
+$arrNumber = str_split($number);
+
+for ($i = 0; $i < 16; $i+=2) {
+    $arrNumber[$i] = $arrNumber[$i]*2;
+    if ($arrNumber[$i]>9)
+       $arrNumber[$i]-=9;
+}
+
+$answer = ["isValid" => "false", "paymentSystem" => "none"];
+
+if (array_sum($arrNumber)%10===0) {
+    $answer["isValid"] = "true";
+    if ($cardNumber[0]==4)
+       $answer["paymentSystem"] = "VISA";
+    elseif ($cardNumber[0]==5)
+       $answer["paymentSystem"] = "Mastercard";
+    elseif ($cardNumber[0]==2 and $cardNumber[1]==2 and $cardNumber[2]==0)
+       $answer["paymentSystem"] = "MIR";
+    else
+       $answer["paymentSystem"] = "UNKNOWN";
+}
+
+print_r($answer);
+
+?>
\ No newline at end of file