diff --git a/C_secure_coding/Dzien1/undeifned1.cpp b/C_secure_coding/Dzien1/undeifned1.cpp
new file mode 100644
index 0000000..aa1afed
--- /dev/null
+++ b/C_secure_coding/Dzien1/undeifned1.cpp
@@ -0,0 +1,9 @@
+#include <iostream>
+
+using namespace std;
+
+int main(){
+	int a = 1;
+	a = a++ + ++a;
+	cout << a << '\n';
+}