crd = list(range(1, list(map(int, input().split()))[0] + 1))
chg = list(map(int, input().split()))
for i in range(len(chg)):
    for j in reversed(range(1, chg[i])):
        crd[j], crd[j - 1] = crd[j - 1], crd[j]
print(crd[0])