100 people in a circle

• 100 people standing in a circle in an order 1 to 100.
• No.1 has a sword.
• He kills next person (i.e. no. 2) and gives sword to next to next (i.e no.3).
• All person does the same until only 1 survives.

Which number survives at the last?

The Answer is an integer. Just put the number without any decimal places.