Buggy python submission (verdict: Time Limit Exceeded):
L, A, B, M = map(int, input().split())

ten = 1

def f(l):
  if l == 0:
    return 0
  if l % 2 == 1:
    pl = l - 1
    x = f(pl)
    return (x * ten + 1) % M
  else:
    pl = l // 2
    x = f(pl)
    return (x * ten ** pl + x) % M

def g(l):
  if l == 0:
    return 0
  if l % 2 == 1:
    pl = l - 1
    x = g(pl)
    return (x * ten + B * pl) % M
  else:
    pl = l // 2
    x = g(pl)
    return (x * ten ** pl + x + B * pl * f(pl)) % M

last = A + B * (L - 1)
ans = 0

for i in range(1, 19):
  l = ten
  r = ten * 10 - 1
  
  if last < l:
    ten *= 10
    continue
  if A > r:
    ten *= 10
    continue
  na = 0 #初項
  nl = 0 #長さ

  if A >= l:
    na = A
  else:
    na = (l - A + B - 1) // B * B + A
    na = min(na, last)
  
  nlast = 0
  if last <= r:
    nlast = last
  else:
    nlast = (r - A) // B * B + A
  nl = (nlast - na) // B + 1

  ten *= 10
  ans *= ten ** nl % M
  ans += (na * f(nl)) % M
  ans += g(nl) % M

print(ans % M)

Fixed submission:
L, A, B, M = map(int, input().split())

ten = 0

def pow_(x, t):
  if t == 0:
    return 1
  if t % 2 == 1:
    return (pow_(x, t - 1) * x) % M
  else:
    y = pow_(x, t // 2)
    return (y * y) % M

def f(l):
  if l == 0:
    return 0
  if l % 2 == 1:
    pl = l - 1
    x = f(pl)
    return x * ten + 1
  else:
    pl = l // 2
    x = f(pl)
    return x * pow_(ten, pl) + x

def g(l):
  if l == 0:
    return 0
  if l % 2 == 1:
    pl = l - 1
    x = g(pl)
    return x * ten + B * pl
  else:
    pl = l // 2
    x = g(pl)
    return x * pow_(ten, pl) + x + B * pl * f(pl)

last = A + B * (L - 1)
ans = 0
ten = 10
for _ in range(18):
  l = ten // 10
  r = ten - 1
  
  if last < l:
    ten *= 10
    continue
  if A > r:
    ten *= 10
    continue
  na = 0 #初項
  nl = 0 #長さ

  if A >= l:
    na = A
  else:
    na = (l - A + B - 1) // B * B + A
    na = min(na, last)
  
  nlast = 0
  if last <= r:
    nlast = last
  else:
    nlast = (r - A) // B * B + A
  nl = (nlast - na) // B + 1

  ans *= pow_(ten, nl) % M
  ans += (na * f(nl)) % M
  ans += g(nl) % M
  ten *= 10

print(ans % M)

Buggy python submission (verdict: Time Limit Exceeded):
L, A, B, M = map(int, input().split())

ten = 1

def f(l):
  if l == 0:
    return 0
  if l % 2 == 1:
    pl = l - 1
    x = f(pl)
    return (x * (ten % M) + 1) % M
  else:
    pl = l // 2
    x = f(pl)
    return (x * (ten % M) ** pl + x) % M

def g(l):
  if l == 0:
    return 0
  if l % 2 == 1:
    pl = l - 1
    x = g(pl)
    return (x * (ten % M) + B * (pl % M)) % M
  else:
    pl = l // 2
    x = g(pl)
    return (x * (ten % M) ** pl + x + B % M * (pl % M) % M * f(pl)) % M

last = A + B * (L - 1)
ans = 0

for i in range(1, 19):
  l = ten
  r = ten * 10 - 1
  
  if last < l:
    ten *= 10
    continue
  if A > r:
    ten *= 10
    continue
  na = 0 #初項
  nl = 0 #長さ

  if A >= l:
    na = A
  else:
    na = (l - A + B - 1) // B * B + A
    na = min(na, last)
  
  nlast = 0
  if last <= r:
    nlast = last
  else:
    nlast = (r - A) // B * B + A
  nl = (nlast - na) // B + 1

  ten *= 10
  ans *= (ten % M) ** nl % M
  ans += (na % M * f(nl) % M) % M
  ans += g(nl) % M

print(ans % M)

Fixed submission:
L, A, B, M = map(int, input().split())

ten = 0

def pow_(x, t):
  if t == 0:
    return 1
  if t % 2 == 1:
    return (pow_(x, t - 1) * x) % M
  else:
    y = pow_(x, t // 2)
    return (y * y) % M

def f(l):
  if l == 0:
    return 0
  if l % 2 == 1:
    pl = l - 1
    x = f(pl)
    return x * ten + 1
  else:
    pl = l // 2
    x = f(pl)
    return x * pow_(ten, pl) + x

def g(l):
  if l == 0:
    return 0
  if l % 2 == 1:
    pl = l - 1
    x = g(pl)
    return x * ten + B * pl
  else:
    pl = l // 2
    x = g(pl)
    return x * pow_(ten, pl) + x + B * pl * f(pl)

last = A + B * (L - 1)
ans = 0
ten = 10
for _ in range(18):
  l = ten // 10
  r = ten - 1
  
  if last < l:
    ten *= 10
    continue
  if A > r:
    ten *= 10
    continue
  na = 0 #初項
  nl = 0 #長さ

  if A >= l:
    na = A
  else:
    na = (l - A + B - 1) // B * B + A
    na = min(na, last)
  
  nlast = 0
  if last <= r:
    nlast = last
  else:
    nlast = (r - A) // B * B + A
  nl = (nlast - na) // B + 1

  ans *= pow_(ten, nl) % M
  ans += (na * f(nl)) % M
  ans += g(nl) % M
  ten *= 10

print(ans % M)

Buggy python submission (verdict: Time Limit Exceeded):
L, A, B, M = map(int, input().split())

ten = 1

def f(l):
  if l == 0:
    return 0
  if l % 2 == 1:
    pl = l - 1
    x = f(pl)
    return (x * (ten % M) + 1) % M
  else:
    pl = l // 2
    x = f(pl)
    return (x * (ten % M) ** pl + x) % M

def g(l):
  if l == 0:
    return 0
  if l % 2 == 1:
    pl = l - 1
    x = g(pl)
    return (x * (ten % M) + B * (pl % M)) % M
  else:
    pl = l // 2
    x = g(pl)
    return (x * (ten % M) ** pl + x + B % M * (pl % M) % M * f(pl)) % M

last = A + B * (L - 1)
ans = 0

for i in range(1, 19):
  l = ten
  r = ten * 10 - 1
  
  if last < l:
    ten *= 10
    continue
  if A > r:
    ten *= 10
    continue
  na = 0 #初項
  nl = 0 #長さ

  if A >= l:
    na = A
  else:
    na = (l - A + B - 1) // B * B + A
    na = min(na, last)
  
  nlast = 0
  if last <= r:
    nlast = last
  else:
    nlast = (r - A) // B * B + A
  nl = (nlast - na) // B + 1

  ten *= 10
  ans *= (ten % M) ** nl % M
  ans += (na % M * f(nl) % M) % M
  ans += g(nl) % M

print(ans % M)

Fixed submission:
L, A, B, M = map(int, input().split())

ten = 0

def pow_(x, t):
  if t == 0:
    return 1
  if t % 2 == 1:
    return (pow_(x, t - 1) * x) % M
  else:
    y = pow_(x, t // 2)
    return (y * y) % M

def f(l):
  if l == 0:
    return 0
  if l % 2 == 1:
    pl = l - 1
    x = f(pl)
    return x * ten + 1
  else:
    pl = l // 2
    x = f(pl)
    return x * pow_(ten, pl) + x

def g(l):
  if l == 0:
    return 0
  if l % 2 == 1:
    pl = l - 1
    x = g(pl)
    return x * ten + B * pl
  else:
    pl = l // 2
    x = g(pl)
    return x * pow_(ten, pl) + x + B * pl * f(pl)

last = A + B * (L - 1)
ans = 0
ten = 10
for _ in range(18):
  l = ten // 10
  r = ten - 1
  
  if last < l:
    ten *= 10
    continue
  if A > r:
    ten *= 10
    continue
  na = 0 #初項
  nl = 0 #長さ

  if A >= l:
    na = A
  else:
    na = (l - A + B - 1) // B * B + A
    na = min(na, last)
  
  nlast = 0
  if last <= r:
    nlast = last
  else:
    nlast = (r - A) // B * B + A
  nl = (nlast - na) // B + 1

  ans *= pow_(ten, nl) % M
  ans += (na * f(nl)) % M
  ans += g(nl) % M
  ten *= 10

print(ans % M)

Buggy python submission (verdict: Time Limit Exceeded):
L, A, B, M = map(int, input().split())

s = ""
for i in range(L):
  s += str(A + B * i)
print(int(s) % M)

Fixed submission:
L, A, B, M = map(int, input().split())

ten = 0

def pow_(x, t):
  if t == 0:
    return 1
  if t % 2 == 1:
    return (pow_(x, t - 1) * x) % M
  else:
    y = pow_(x, t // 2)
    return (y * y) % M

def f(l):
  if l == 0:
    return 0
  if l % 2 == 1:
    pl = l - 1
    x = f(pl)
    return x * ten + 1
  else:
    pl = l // 2
    x = f(pl)
    return x * pow_(ten, pl) + x

def g(l):
  if l == 0:
    return 0
  if l % 2 == 1:
    pl = l - 1
    x = g(pl)
    return x * ten + B * pl
  else:
    pl = l // 2
    x = g(pl)
    return x * pow_(ten, pl) + x + B * pl * f(pl)

last = A + B * (L - 1)
ans = 0
ten = 10
for _ in range(18):
  l = ten // 10
  r = ten - 1
  
  if last < l:
    ten *= 10
    continue
  if A > r:
    ten *= 10
    continue
  na = 0 #初項
  nl = 0 #長さ

  if A >= l:
    na = A
  else:
    na = (l - A + B - 1) // B * B + A
    na = min(na, last)
  
  nlast = 0
  if last <= r:
    nlast = last
  else:
    nlast = (r - A) // B * B + A
  nl = (nlast - na) // B + 1

  ans *= pow_(ten, nl) % M
  ans += (na * f(nl)) % M
  ans += g(nl) % M
  ten *= 10

print(ans % M)