Here is the full list of all 100 POG 4 achievements.
Level 50
Sign 24
Level 49
Sign 23
Level 48
Sign 22
Level 47
Sign 21
Level 46
Sign 20
Level 45
Sign 19
Level 44
Sign 18
Level 43
Sign 17
Level 42
Sign 16
Level 41
Sign 15
Level 40
Sign 14
Level 39
Sign 13
Level 38
Sign 12
Level 37
Sign 11
Level 36
Sign 10
Level 35
Sign 9
Level 34
Sign 8
Level 33
Sign 7
Sign 6
Level 32
Sign 5
Level 31
Level 30
Sign 4
Level 29
Sign 3
Level 28
Sign 2
Level 27
Sign 1
Level 26
Z
Level 25
Y
Level 24
X
W
Level 23
Level 22
V
Level 21
U
Level 20
T
Level 19
Level 18
S
Level 17
R
Level 16
P
Level 15
Level 14
N
Level 13
Level 12
L
Level 11
Level 10
K
Level 9
I
Level 8
H
Level 7
G
Level 6
F
E
Level 5
Level 4
D
Level 3
C
Level 2
B
Level 1
A