N,sf=map(int,input().split())
lsc=[]
for i in range(1,N+1):
    lsc.append(i)
lsy=list(map(int,input().split()))
for i in range(len(lsy)):
    ix=lsy[i]-1
    po=lsc.pop(ix)
    lsc.insert(0,po)
print(lsc[0])