n = int(input())
r = list(map(int, input().split()))

current_end = 1
current_max = 1
steps = 0

for i in range(1, n):  # i是1-based的城镇编号
    if i > current_end:
        break  # 这种情况不会出现，根据题意数据保证可达N
    current_max = max(current_max, r[i-1])  # 输入中的第i-1个元素对应城镇i的R_i
    if i == current_end:
        steps += 1
        if current_max >= n:
            break
        current_end = current_max

print(steps)