Buggy python submission (verdict: Runtime Error):
import numpy as np
N,K=map(int,input().split())
a=[[int(i) for i in input().split()] for _ in range(N)]
a=np.array(a,dtype=np.int64)
MOD=10**9+7

def matmul(A,B,MOD):
    N=len(A)
    C=np.zeros((N,N),dtype=np.int64)

    for n in range(N):
        C[n] = (A[n,:][:,None] * B % mod).sum(axis=0) % mod
    return C

def mat_power(A,k,MOD):
    N=len(A)
    D=np.identity(N,dtype=np.int64)
    while k:
        if k & 1:
            D=matmul(D,A,MOD)
        A = matmul(A,A,MOD)
        k >>= 1

    return D

A=mat_power(a,K,MOD)
ans=0
for i in range(N):
    for j in range(N):
        ans=(ans+A[i][j])%MOD

print(ans)

Fixed submission:
import numpy as np
N,K=map(int,input().split())
a=[[int(i) for i in input().split()] for _ in range(N)]
a=np.array(a,dtype=np.int64)
MOD=10**9+7

def matmul(A,B,MOD):
    N=len(A)
    C=np.zeros((N,N),dtype=np.int64)

    for n in range(N):
        C[n] = (A[n,:][:,None] * B % MOD).sum(axis=0) % MOD
    return C

def mat_power(A,k,MOD):
    N=len(A)
    D=np.identity(N,dtype=np.int64)
    while k:
        if k & 1:
            D=matmul(D,A,MOD)
        A = matmul(A,A,MOD)
        k >>= 1

    return D

A=mat_power(a,K,MOD)
ans=0
for i in range(N):
    for j in range(N):
        ans=(ans+A[i][j])%MOD

print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
import numpy as np
N,K=map(int,input().split())
a=[[int(i) for i in input().split()] for _ in range(N)]
a=np.array(a,dtype=np.int64)
MOD=10**9+7

def matmul(A,B,MOD):
    N=len(A)
    C=np.zeros((N,N),dtype=np.int64)

    for i in range(N):
        for j in range(N):
            for k in range(N):
                C[i][j] =(C[i][j]+ A[i][k]*B[k][j])%MOD
    return C

def mat_power(A,k,MOD):
    N=len(A)
    D=np.identity(N,dtype=np.int64)
    while k:
        if k & 1:
            D=matmul(D,A,MOD)
        A = matmul(A,A,MOD)
        k >>= 1

    return D

A=mat_power(a,K,MOD)
ans=0
for i in range(N):
    for j in range(N):
        ans=(ans+A[i][j])%MOD

print(ans)


Fixed submission:
import numpy as np
N,K=map(int,input().split())
a=[[int(i) for i in input().split()] for _ in range(N)]
a=np.array(a,dtype=np.int64)
MOD=10**9+7

def matmul(A,B,MOD):
    N=len(A)
    C=np.zeros((N,N),dtype=np.int64)

    for n in range(N):
        C[n] = (A[n,:][:,None] * B % MOD).sum(axis=0) % MOD
    return C

def mat_power(A,k,MOD):
    N=len(A)
    D=np.identity(N,dtype=np.int64)
    while k:
        if k & 1:
            D=matmul(D,A,MOD)
        A = matmul(A,A,MOD)
        k >>= 1

    return D

A=mat_power(a,K,MOD)
ans=0
for i in range(N):
    for j in range(N):
        ans=(ans+A[i][j])%MOD

print(ans)

Buggy python submission (verdict: Runtime Error):
import numpy as np
N,K=map(int,input().split())
a=[[int(i) for i in input().split()] for _ in range(N)]
a=np.array(a,dtype=np.int64)
MOD=10**9+7

def matmul(A,B,MOD):
    N=len(A)
    C=np.zeros(N,dtype=np.int64)
    for i in range(N):
        for j in range(N):
            for k in range(N):
                C[i][j] += A[i][k]*B[k][j]%MOD
    return C

def mat_power(A,k,MOD):
    N=len(A)
    D=np.identity(N,dtype=np.int64)
    while k:
        if k & 1:
            D=matmul(D,A,MOD)
        A = matmul(A,A,MOD)
        k >>= 1

    return D

A=mat_power(a,K,MOD)
ans=0
for i in range(N):
    for j in range(N):
        ans=(ans+A[i][j])%MOD

print(ans)


Fixed submission:
import numpy as np
N,K=map(int,input().split())
a=[[int(i) for i in input().split()] for _ in range(N)]
a=np.array(a,dtype=np.int64)
MOD=10**9+7

def matmul(A,B,MOD):
    N=len(A)
    C=np.zeros((N,N),dtype=np.int64)

    for n in range(N):
        C[n] = (A[n,:][:,None] * B % MOD).sum(axis=0) % MOD
    return C

def mat_power(A,k,MOD):
    N=len(A)
    D=np.identity(N,dtype=np.int64)
    while k:
        if k & 1:
            D=matmul(D,A,MOD)
        A = matmul(A,A,MOD)
        k >>= 1

    return D

A=mat_power(a,K,MOD)
ans=0
for i in range(N):
    for j in range(N):
        ans=(ans+A[i][j])%MOD

print(ans)

Buggy python submission (verdict: Runtime Error):
import numpy as np
N,K=map(int,input().split())
a=[[int(i) for i in input().split()] for _ in range(N)]
a=np.array(a,dtype=np.int64)
MOD=10**9+7

def matmul(A,B,MOD):
    N=len(A)
    C=np.zeros(N,dtype=np.int64)
    for i in range(N):
        for j in range(N):
            for k in range(N):
            C[i][j] += A[i][k]B[k][j]%MOD
    return C

def mat_power(A,k,MOD):
    N=len(A)
    D=np.identity(N,dtype=np.int64)
    while k:
        if k & 1:
            D=matmul(D,A,MOD)
        A = matmul(A,A,MOD)
        k >>= 1

    return D

A=mat_power(a,K,MOD)
ans=0
for i in range(N):
    for j in range(N):
        ans=(ans+A[i][j])%MOD

print(ans)

Fixed submission:
import numpy as np
N,K=map(int,input().split())
a=[[int(i) for i in input().split()] for _ in range(N)]
a=np.array(a,dtype=np.int64)
MOD=10**9+7

def matmul(A,B,MOD):
    N=len(A)
    C=np.zeros((N,N),dtype=np.int64)

    for n in range(N):
        C[n] = (A[n,:][:,None] * B % MOD).sum(axis=0) % MOD
    return C

def mat_power(A,k,MOD):
    N=len(A)
    D=np.identity(N,dtype=np.int64)
    while k:
        if k & 1:
            D=matmul(D,A,MOD)
        A = matmul(A,A,MOD)
        k >>= 1

    return D

A=mat_power(a,K,MOD)
ans=0
for i in range(N):
    for j in range(N):
        ans=(ans+A[i][j])%MOD

print(ans)