Buggy python submission (verdict: Time Limit Exceeded):
from math import ceil
def dot(a,b,m):
    c = [[0,0,0],[0,0,0],[0,0,0]]
    for i in range(3):
        for j in range(3):
            for k in range(3):
                c[i][j] += a[i][k]*b[k][j]
                c[i][j] %= m
    return c
def powm(a,n,m):
    if n == 0:
        return [[1,0,0],[0,1,0],[0,0,1]]
    for i in range(3):
        for j in range(3):
            a[i][j] %= m
    if n%2==0:
        return dot(powm(a,n//2,m),powm(a,n//2,m),m)
    else:
        return dot(dot(powm(a,n//2,m),powm(a,n//2,m),m),a,m)

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

a = [[1,0,0],[0,1,0],[0,0,1]]
for d in range(1,19):
    C = min(max(0,ceil((10**d-A)/B)),L)-min(max(0,ceil((10**(d-1)-A)/B)),L)
    a = dot(powm([[pow(10,d,M),1,0],[0,1,B%M],[0,0,1]],C,M),a,M)
ans = (a[0][1]*A+a[0][2])%M
print(ans)

Fixed submission:
def dot(a,b,m):
    c = [[0,0,0],[0,0,0],[0,0,0]]
    for i in range(3):
        for j in range(3):
            for k in range(3):
                c[i][j] += a[i][k]*b[k][j]
                c[i][j] %= m
    return c
    
def powm(a,n,m):
    if n == 0:
        return [[1,0,0],[0,1,0],[0,0,1]]
    for i in range(3):
        for j in range(3):
            a[i][j] %= m
    r = powm(a,n//2,m)
    if n%2==0:
        return dot(r,r,m)
    else:
        return dot(dot(r,r,m),a,m)

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

a = [[1,0,0],[0,1,0],[0,0,1]]
for d in range(1,19):
    C = min(max(0,(10**d-A-1)//B+1),L)-min(max(0,(10**(d-1)-A-1)//B+1),L)
    a = dot(powm([[pow(10,d,M),1,0],[0,1,B%M],[0,0,1]],C,M),a,M)
ans = (a[0][1]*A%M+a[0][2])%M
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
from math import ceil
def dot(a,b,m):
    c = [[0,0,0],[0,0,0],[0,0,0]]
    for i in range(3):
        for j in range(3):
            for k in range(3):
                c[i][j] += a[i][k]*b[k][j]
                c[i][j] %= m
    return c
def powm(a,n,m):
    if n == 0:
        return [[1,0,0],[0,1,0],[0,0,1]]
    for i in range(3):
        for j in range(3):
            a[i][j] %= m
    if n%2==0:
        return dot(powm(a,n//2,m),powm(a,n//2,m),m)
    else:
        return dot(dot(powm(a,n//2,m),powm(a,n//2,m),m),a,m)

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

a = [[1,0,0],[0,1,0],[0,0,1]]
for d in range(1,19):
    C = min(max(0,ceil((10**d-A)/B)),L)-min(max(0,ceil((10**(d-1)-A)/B)),L)
    a = dot(powm([[pow(10,d,M),1,0],[0,1,B%M],[0,0,1]],C,M),a,M)
ans = (a[0][1]*A+a[0][2])%M
print(ans)

Fixed submission:
def dot(a,b,m):
    c = [[0,0,0],[0,0,0],[0,0,0]]
    for i in range(3):
        for j in range(3):
            for k in range(3):
                c[i][j] += a[i][k]*b[k][j]
                c[i][j] %= m
    return c
    
def powm(a,n,m):
    if n == 0:
        return [[1,0,0],[0,1,0],[0,0,1]]
    for i in range(3):
        for j in range(3):
            a[i][j] %= m
    r = powm(a,n//2,m)
    if n%2==0:
        return dot(r,r,m)
    else:
        return dot(dot(r,r,m),a,m)

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

a = [[1,0,0],[0,1,0],[0,0,1]]
for d in range(1,19):
    C = min(max(0,(10**d-A-1)//B+1),L)-min(max(0,(10**(d-1)-A-1)//B+1),L)
    a = dot(powm([[pow(10,d,M),1,0],[0,1,B%M],[0,0,1]],C,M),a,M)
ans = (a[0][1]*A%M+a[0][2])%M
print(ans)

Buggy python submission (verdict: Runtime Error):
import numpy as np
from math import ceil
def powm(a,n,m):
    if n == 0:
        return np.eye(len(a))
    if n%2==0:
        return np.dot(powm(a,n//2,m),powm(a,n//2,m))%m
    else:
        return np.dot(np.dot(powm(a,n//2,m),powm(a,n//2,m)),a)%m

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

C = [0]*18
d = 0
while True:
    C[d] = max(0,min(ceil((10**d-A)/B),L))
    if C[d] == L:
        break
    d += 1

for d in range(17,-1,-1):
    if C[d] != 0:
        C[d] -= C[d-1]

a = np.eye(3)
for d in range(1,18):
    a = np.dot(powm(np.array([[10**d%M,1,0],[0,1,B],[0,0,1]]),C[d],M),a)

ans = int(np.dot(a,np.array([0,A,1]))[0])%M

print(ans)

Fixed submission:
def dot(a,b,m):
    c = [[0,0,0],[0,0,0],[0,0,0]]
    for i in range(3):
        for j in range(3):
            for k in range(3):
                c[i][j] += a[i][k]*b[k][j]
                c[i][j] %= m
    return c
    
def powm(a,n,m):
    if n == 0:
        return [[1,0,0],[0,1,0],[0,0,1]]
    for i in range(3):
        for j in range(3):
            a[i][j] %= m
    r = powm(a,n//2,m)
    if n%2==0:
        return dot(r,r,m)
    else:
        return dot(dot(r,r,m),a,m)

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

a = [[1,0,0],[0,1,0],[0,0,1]]
for d in range(1,19):
    C = min(max(0,(10**d-A-1)//B+1),L)-min(max(0,(10**(d-1)-A-1)//B+1),L)
    a = dot(powm([[pow(10,d,M),1,0],[0,1,B%M],[0,0,1]],C,M),a,M)
ans = (a[0][1]*A%M+a[0][2])%M
print(ans)