N,M = map(int, raw_input().split())
A = map(int, raw_input().split())
pos = [0] * (N + 1)
for i in range(1, N + 1):
    pos[i] = i

for x in A:
    pos[0] = pos[x]
    for y in range(1, x + 1):
        pos[y] = pos[y - 1]
print pos[0]