def substring_pos(a: str, b: str) -> int:
for i in range(len(a) - len(b)):
j = 0
while j < len(b) and b[j] == a[i + j]:
j += 1
if j == len(b):
return i
return -1
a = "alamakota"
b = "kot"
pos = substring_pos(a, b)
if pos == -1:
print(f'{b} is not a substring of {a}')
else:
print(f'{b} is substring of {a} and starts at position {pos}')