# -*- coding: utf-8 -*-
N, M = map(int, raw_input().split())
CARD = [i for i in range(1,N+1)]
SHF = map(int, raw_input().split())
for i in range(0, M):
    tmp = CARD.pop(SHF[i]-1)
    CARD.insert(0,tmp)
print CARD[0]