# -*- coding:utf-8 -*-

if __name__ == "__main__":
	n,m = map(int,raw_input().split())
	a = map(int,raw_input().split())
	card = range(1,n+1)
	for i in a:
		card = card[i-1:i] + card[:i-1] + card[i:]
	print card[0]