Buggy python submission (verdict: Runtime Error):
import itertools

n, m, k = map(int, input().split())


def cmb(n, r, p):
    if (r < 0) or (n < r):
        return 0
    r = min(r, n - r)
    return fact[n] * factinv[r] * factinv[n-r] % p


p = 998244353
N = n   # N は必要分だけ用意する
fact = [1, 1]  # fact[n] = (n! mod p)
factinv = [1, 1]  # factinv[n] = ((n!)^(-1) mod p)
inv = [0, 1]  # factinv 計算用

for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p)

ans = 0

l2 = m*(m-1)**(n-k-2)
for _k in range(k, -1, -1):
    # print(_k)

    l2 %= p
    l2 *= (m - 1)
    l2 %= p

    ncr = cmb(n - 1, _k, p)
    ans += ncr * l2
    ans %= p


print(ans)


Fixed submission:
import itertools

n, m, k = map(int, input().split())


def cmb(n, r, p):
    if (r < 0) or (n < r):
        return 0
    r = min(r, n - r)
    return fact[n] * factinv[r] * factinv[n-r] % p


p = 998244353
N = n   # N は必要分だけ用意する
fact = [1, 1]  # fact[n] = (n! mod p)
factinv = [1, 1]  # factinv[n] = ((n!)^(-1) mod p)
inv = [0, 1]  # factinv 計算用

for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p)

ans = 0

l2 = m*(m-1)**(n-k-1)
for _k in range(k, -1, -1):
    # print(_k)

    ncr = cmb(n - 1, _k, p)
    ans += ncr * l2
    ans %= p
    l2 %= p
    l2 *= (m - 1)


print(ans)

Buggy python submission (verdict: Runtime Error):
import itertools

n, m, k = map(int, input().split())


def cmb(n, r, p):
    if (r < 0) or (n < r):
        return 0
    r = min(r, n - r)
    return fact[n] * factinv[r] * factinv[n-r] % p


p = 998244353
N = n   # N は必要分だけ用意する
fact = [1, 1]  # fact[n] = (n! mod p)
factinv = [1, 1]  # factinv[n] = ((n!)^(-1) mod p)
inv = [0, 1]  # factinv 計算用

for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p)

ans = 0

l2 = m*(m-1)**(n-k-2)
for _k in range(k, -1, -1):
    # print(_k)

    l2 %= p
    l2 *= (m - 1)

    ncr = cmb(n - 1, _k, p)
    ans += ncr * l2
    ans %= p


print(ans)


Fixed submission:
import itertools

n, m, k = map(int, input().split())


def cmb(n, r, p):
    if (r < 0) or (n < r):
        return 0
    r = min(r, n - r)
    return fact[n] * factinv[r] * factinv[n-r] % p


p = 998244353
N = n   # N は必要分だけ用意する
fact = [1, 1]  # fact[n] = (n! mod p)
factinv = [1, 1]  # factinv[n] = ((n!)^(-1) mod p)
inv = [0, 1]  # factinv 計算用

for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p)

ans = 0

l2 = m*(m-1)**(n-k-1)
for _k in range(k, -1, -1):
    # print(_k)

    ncr = cmb(n - 1, _k, p)
    ans += ncr * l2
    ans %= p
    l2 %= p
    l2 *= (m - 1)


print(ans)

Buggy python submission (verdict: Runtime Error):
import itertools

n, m, k = map(int, input().split())


def cmb(n, r, p):
    if (r < 0) or (n < r):
        return 0
    r = min(r, n - r)
    return fact[n] * factinv[r] * factinv[n-r] % p


p = 998244353
N = n   # N は必要分だけ用意する
fact = [1, 1]  # fact[n] = (n! mod p)
factinv = [1, 1]  # factinv[n] = ((n!)^(-1) mod p)
inv = [0, 1]  # factinv 計算用

for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p)

ans = 0

l2 = m*(m-1)**(n-k-2)
for _k in range(k, -1, -1):
    # print(_k)
    l2 *= (m - 1)
    l2 %= p
    ncr = cmb(n - 1, _k, p)
    ans += ncr * l2
    ans %= p


print(ans)


Fixed submission:
import itertools

n, m, k = map(int, input().split())


def cmb(n, r, p):
    if (r < 0) or (n < r):
        return 0
    r = min(r, n - r)
    return fact[n] * factinv[r] * factinv[n-r] % p


p = 998244353
N = n   # N は必要分だけ用意する
fact = [1, 1]  # fact[n] = (n! mod p)
factinv = [1, 1]  # factinv[n] = ((n!)^(-1) mod p)
inv = [0, 1]  # factinv 計算用

for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p)

ans = 0

l2 = m*(m-1)**(n-k-1)
for _k in range(k, -1, -1):
    # print(_k)

    ncr = cmb(n - 1, _k, p)
    ans += ncr * l2
    ans %= p
    l2 %= p
    l2 *= (m - 1)


print(ans)