N,M=(int(i) for i in input (). split ())
A=[int (i) for i in input (). split ()]
#rint (A)
C=[int (i+1) for i in range(N)]
#rint (C)
for i in range (M):
    R=C[A[i]-1]
    C.pop(A[i]-1)
 #   print(C)
    C.insert(0,R)
  #  print (C)
print (C[0])