import sys

def LI(): return list(map(int, sys.stdin.buffer.readline().split()))

def I(): return int(sys.stdin.buffer.readline())

def LS(): return sys.stdin.buffer.readline().rstrip().decode('utf-8').split()

def S(): return sys.stdin.buffer.readline().rstrip().decode('utf-8')

def IR(n): return [I() for i in range(n)]

def LIR(n): return [LI() for i in range(n)]

def SR(n): return [S() for i in range(n)]

def LSR(n): return [LS() for i in range(n)]

def SRL(n): return [list(S()) for i in range(n)]

def MSRL(n): return [[int(j) for j in list(S())] for i in range(n)]

mod = 10 ** 9 + 7



n = I()

hl = LI()

wl = []

count = 0



len_h = len(hl)



def m1(n):

    if n > 0:

        n = n - 1

    else:

        n = 0

    return n



max_hana = max(hl)

if max_hana == 0:

    print((0))

    sys.exit()



for i in range(max_hana):

    for j in range(len_h):

        if j == 0:

            if hl[j] > 0:

                count += 1

        else:

            if hl[j] > 0 and hl[j-1] == 0:

                count += 1

            elif hl[j] > 0 and hl[j-1] == 0:

                count += 1

    hl = list(map(m1, hl))



print(count)
import sys

def LI(): return list(map(int, sys.stdin.buffer.readline().split()))

def I(): return int(sys.stdin.buffer.readline())

def LS(): return sys.stdin.buffer.readline().rstrip().decode('utf-8').split()

def S(): return sys.stdin.buffer.readline().rstrip().decode('utf-8')

def IR(n): return [I() for i in range(n)]

def LIR(n): return [LI() for i in range(n)]

def SR(n): return [S() for i in range(n)]

def LSR(n): return [LS() for i in range(n)]

def SRL(n): return [list(S()) for i in range(n)]

def MSRL(n): return [[int(j) for j in list(S())] for i in range(n)]

mod = 10 ** 9 + 7



n = I()

hl = LI()

# count = 0



# len_h = len(hl)



# def m1(n):

#     if n > 0:

#         n = n - 1

#     else:

#         n = 0

#     return n



# max_hana = max(hl)

# if max_hana == 0:

#     print(0)

#     sys.exit()



# for i in range(max_hana):

#     for j in range(len_h):

#         if j == 0:

#             if hl[j] > 0:

#                 count += 1

#         else:

#             if hl[j] > 0 and hl[j-1] == 0:

#                 count += 1

#             elif hl[j] > 0 and hl[j-1] == 0:

#                 count += 1

#     hl = list(map(m1, hl))



# print(count)



######################

# 隣との差分を考えたほうが早い



# 1    2    4    2    1    0      計4

#   1    2    0    0     0



ans = hl[0]

for i in range(1, n):

    ans += max(0, hl[i] - hl[i - 1])

print(ans)



import sys


def LI():
    return list(map(int, sys.stdin.buffer.readline().split()))


def I():
    return int(sys.stdin.buffer.readline())


def LS():
    return sys.stdin.buffer.readline().rstrip().decode("utf-8").split()


def S():
    return sys.stdin.buffer.readline().rstrip().decode("utf-8")


def IR(n):
    return [I() for i in range(n)]


def LIR(n):
    return [LI() for i in range(n)]


def SR(n):
    return [S() for i in range(n)]


def LSR(n):
    return [LS() for i in range(n)]


def SRL(n):
    return [list(S()) for i in range(n)]


def MSRL(n):
    return [[int(j) for j in list(S())] for i in range(n)]


mod = 10**9 + 7
n = I()
hl = LI()
wl = []
count = 0
len_h = len(hl)


def m1(n):
    if n > 0:
        n = n - 1
    else:
        n = 0
    return n


max_hana = max(hl)
if max_hana == 0:
    print((0))
    sys.exit()
for i in range(max_hana):
    for j in range(len_h):
        if j == 0:
            if hl[j] > 0:
                count += 1
        else:
            if hl[j] > 0 and hl[j - 1] == 0:
                count += 1
            elif hl[j] > 0 and hl[j - 1] == 0:
                count += 1
    hl = list(map(m1, hl))
print(count)

import sys


def LI():
    return list(map(int, sys.stdin.buffer.readline().split()))


def I():
    return int(sys.stdin.buffer.readline())


def LS():
    return sys.stdin.buffer.readline().rstrip().decode("utf-8").split()


def S():
    return sys.stdin.buffer.readline().rstrip().decode("utf-8")


def IR(n):
    return [I() for i in range(n)]


def LIR(n):
    return [LI() for i in range(n)]


def SR(n):
    return [S() for i in range(n)]


def LSR(n):
    return [LS() for i in range(n)]


def SRL(n):
    return [list(S()) for i in range(n)]


def MSRL(n):
    return [[int(j) for j in list(S())] for i in range(n)]


mod = 10**9 + 7
n = I()
hl = LI()
# count = 0
# len_h = len(hl)
# def m1(n):
#     if n > 0:
#         n = n - 1
#     else:
#         n = 0
#     return n
# max_hana = max(hl)
# if max_hana == 0:
#     print(0)
#     sys.exit()
# for i in range(max_hana):
#     for j in range(len_h):
#         if j == 0:
#             if hl[j] > 0:
#                 count += 1
#         else:
#             if hl[j] > 0 and hl[j-1] == 0:
#                 count += 1
#             elif hl[j] > 0 and hl[j-1] == 0:
#                 count += 1
#     hl = list(map(m1, hl))
# print(count)
######################
# 隣との差分を考えたほうが早い
# 1    2    4    2    1    0      計4
#   1    2    0    0     0
ans = hl[0]
for i in range(1, n):
    ans += max(0, hl[i] - hl[i - 1])
print(ans)

-wl = [] -count = 0 -len_h = len(hl) - - -def m1(n): -    if n > 0: -        n = n - 1 -    else: -        n = 0 -    return n - - -max_hana = max(hl) -if max_hana == 0: -    print((0)) -    sys.exit() -for i in range(max_hana): -    for j in range(len_h): -        if j == 0: -            if hl[j] > 0: -                count += 1 -        else: -            if hl[j] > 0 and hl[j - 1] == 0: -                count += 1 -            elif hl[j] > 0 and hl[j - 1] == 0: -                count += 1 -    hl = list(map(m1, hl)) -print(count) +# count = 0 +# len_h = len(hl) +# def m1(n): +#     if n > 0: +#         n = n - 1 +#     else: +#         n = 0 +#     return n +# max_hana = max(hl) +# if max_hana == 0: +#     print(0) +#     sys.exit() +# for i in range(max_hana): +#     for j in range(len_h): +#         if j == 0: +#             if hl[j] > 0: +#                 count += 1 +#         else: +#             if hl[j] > 0 and hl[j-1] == 0: +#                 count += 1 +#             elif hl[j] > 0 and hl[j-1] == 0: +#                 count += 1 +#     hl = list(map(m1, hl)) +# print(count) +###################### +# 隣との差分を考えたほうが早い +# 1    2    4    2    1    0      計4 +#   1    2    0    0     0 +ans = hl[0] +for i in range(1, n): +    ans += max(0, hl[i] - hl[i - 1]) +print(ans)