#coding: utf-8
##yuki_123

nm=[]
nm=map(int,raw_input().split())
a=[]
a=map(int,raw_input().split())

n=nm[0]
m=nm[1]

narr=[x+1 for x in xrange(n)]

for i in xrange(m):
 narr.insert(0,narr.pop(a[i]-1))

print narr[0]