BTW, "Казнить нельзя помиловать" is a famous expression that schoolchildren learn to remind them about the importance of correctly placing commas. If you put the comma between the first word and the second word:

Казнить, нельзя помиловать!

The meaning is "Put (this person) to death! Do not pardon!"


But if the comma goes between the second word and the third word:

Казнить нельзя, помиловать!

Then the meaning is "Do NOT execute (this person)! Grant (him) clemency!"