Buggy python submission (verdict: Time Limit Exceeded):
import math
MOD = 998244353
N,M,K = [int(hoge) for hoge in input().split()]
NcK = []
POWER = []
cur = 1#Nc0
for k in range(K+1):
    NcK.append(cur % MOD)
    cur *= (N-1-k)
    if k==K:break
    cur //= (k+1)    

ans = 0
Power = 1
for k in range(N-1-K):#M-1**n-1-K
    Power *= M-1
    Power %= MOD

for k in range(K,-1,-1):
    ans += Power * NcK[k]
        #M-1 ** N-1-k ということは…？
    if k:
        Power *= M-1
        Power %= MOD
    

print((M*ans)%MOD)


Fixed submission:
#互いに素なa,bについて、a*x+b*y=1の一つの解
def extgcd(a,b):
    r = [1,0,a]
    w = [0,1,b]
    while w[2]!=1:
        q = r[2]//w[2]
        r2 = w
        w2 = [r[0]-q*w[0],r[1]-q*w[1],r[2]-q*w[2]]
        r = r2
        w = w2
    #[x,y]
    return [w[0],w[1]]

# aの逆元(mod m)を求める。(aとmは互いに素であることが前提)
def mod_inv(a,m):
    x = extgcd(a,m)[0]
    return (m+x%m)%m

import math
MOD = 998244353
N,M,K = [int(hoge) for hoge in input().split()]
NcK = []
POWER = []
cur = 1#Nc0
for k in range(K+1):
    NcK.append(cur)
    cur *= (N-1-k)* mod_inv(k+1,MOD)
    cur %= MOD    

ans = 0
Power = 1
for k in range(N-1-K):#M-1**n-1-K
    Power *= M-1
    Power %= MOD

for k in range(K,-1,-1):
    ans += Power * NcK[k]
        #M-1 ** N-1-k ということは…？
    if k:
        Power *= M-1
        Power %= MOD
    

print((M*ans)%MOD)

Buggy python submission (verdict: Time Limit Exceeded):
import math
MOD = 998244353
N,M,K = [int(hoge) for hoge in input().split()]
NcK = []
POWER = []
cur = 1#Nc0
for k in range(K+1):
    NcK.append(cur % MOD)
    cur *= (N-1-k)
    if k==K:break
    cur //= (k+1)    

ans = 0
Power = 1
for k in range(N-1-K):#M-1**n-1-K
    Power *= M-1
    Power %= MOD

for k in range(K,-1,-1):
    ans += Power * NcK[k]
        #M-1 ** N-1-k ということは…？
    if k:
        Power *= M-1

print((M*ans)%MOD)


Fixed submission:
#互いに素なa,bについて、a*x+b*y=1の一つの解
def extgcd(a,b):
    r = [1,0,a]
    w = [0,1,b]
    while w[2]!=1:
        q = r[2]//w[2]
        r2 = w
        w2 = [r[0]-q*w[0],r[1]-q*w[1],r[2]-q*w[2]]
        r = r2
        w = w2
    #[x,y]
    return [w[0],w[1]]

# aの逆元(mod m)を求める。(aとmは互いに素であることが前提)
def mod_inv(a,m):
    x = extgcd(a,m)[0]
    return (m+x%m)%m

import math
MOD = 998244353
N,M,K = [int(hoge) for hoge in input().split()]
NcK = []
POWER = []
cur = 1#Nc0
for k in range(K+1):
    NcK.append(cur)
    cur *= (N-1-k)* mod_inv(k+1,MOD)
    cur %= MOD    

ans = 0
Power = 1
for k in range(N-1-K):#M-1**n-1-K
    Power *= M-1
    Power %= MOD

for k in range(K,-1,-1):
    ans += Power * NcK[k]
        #M-1 ** N-1-k ということは…？
    if k:
        Power *= M-1
        Power %= MOD
    

print((M*ans)%MOD)

Buggy python submission (verdict: Time Limit Exceeded):
MOD = 998244353
N,M,K = [int(hoge) for hoge in input().split()]
NcK = []
POWER = []
cur = 1#Nc0
for k in range(K+1):
    NcK.append(cur % MOD)
    cur *= (N-1-k)
    if k==K:break
    cur //= (k+1)    
curpower = 1
for n in range(N):#M-1 ** n
   POWER.append(curpower)
   curpower *= M-1
   curpower %= MOD

ans = 0

for k in range(K+1):
    ans += M * POWER[N-1-k] * NcK[k]
    #M-1 ** N-1-k ということは…？
ans %= MOD
print(ans)


Fixed submission:
#互いに素なa,bについて、a*x+b*y=1の一つの解
def extgcd(a,b):
    r = [1,0,a]
    w = [0,1,b]
    while w[2]!=1:
        q = r[2]//w[2]
        r2 = w
        w2 = [r[0]-q*w[0],r[1]-q*w[1],r[2]-q*w[2]]
        r = r2
        w = w2
    #[x,y]
    return [w[0],w[1]]

# aの逆元(mod m)を求める。(aとmは互いに素であることが前提)
def mod_inv(a,m):
    x = extgcd(a,m)[0]
    return (m+x%m)%m

import math
MOD = 998244353
N,M,K = [int(hoge) for hoge in input().split()]
NcK = []
POWER = []
cur = 1#Nc0
for k in range(K+1):
    NcK.append(cur)
    cur *= (N-1-k)* mod_inv(k+1,MOD)
    cur %= MOD    

ans = 0
Power = 1
for k in range(N-1-K):#M-1**n-1-K
    Power *= M-1
    Power %= MOD

for k in range(K,-1,-1):
    ans += Power * NcK[k]
        #M-1 ** N-1-k ということは…？
    if k:
        Power *= M-1
        Power %= MOD
    

print((M*ans)%MOD)

Buggy python submission (verdict: Time Limit Exceeded):
MOD = 998244353
N,M,K = [int(hoge) for hoge in input().split()]
NcK = []
POWER = []
cur = 1#Nc0
for k in range(K+1):
    NcK.append(cur % MOD)
    cur *= (N-1-k)
    if k==K:break
    cur //= (k+1)    
curpower = 1
for n in range(N):#M-1 ** n
   POWER.append(curpower)
   curpower *= M-1
   curpower %= MOD

ans = 0

for k in range(K+1):
    ans += M * POWER[N-1-k] * NcK[k]
    #M-1 ** N-1-k ということは…？
    ans %= MOD
print(ans)

Fixed submission:
#互いに素なa,bについて、a*x+b*y=1の一つの解
def extgcd(a,b):
    r = [1,0,a]
    w = [0,1,b]
    while w[2]!=1:
        q = r[2]//w[2]
        r2 = w
        w2 = [r[0]-q*w[0],r[1]-q*w[1],r[2]-q*w[2]]
        r = r2
        w = w2
    #[x,y]
    return [w[0],w[1]]

# aの逆元(mod m)を求める。(aとmは互いに素であることが前提)
def mod_inv(a,m):
    x = extgcd(a,m)[0]
    return (m+x%m)%m

import math
MOD = 998244353
N,M,K = [int(hoge) for hoge in input().split()]
NcK = []
POWER = []
cur = 1#Nc0
for k in range(K+1):
    NcK.append(cur)
    cur *= (N-1-k)* mod_inv(k+1,MOD)
    cur %= MOD    

ans = 0
Power = 1
for k in range(N-1-K):#M-1**n-1-K
    Power *= M-1
    Power %= MOD

for k in range(K,-1,-1):
    ans += Power * NcK[k]
        #M-1 ** N-1-k ということは…？
    if k:
        Power *= M-1
        Power %= MOD
    

print((M*ans)%MOD)

Buggy python submission (verdict: Time Limit Exceeded):
MOD = 998244353
N,M,K = [int(hoge) for hoge in input().split()]
NcK = []
cur = 1#Nc0
for k in range(K+1):
    NcK.append(cur)
    cur *= (N-1-k)
    if k==K:break
    cur //= (k+1)    

ans = 0
def power_func(a,n,p):#a**n mod P
  bi=str(format(n,"b"))#2進表現に
  res=1
  for i in range(len(bi)):
    res=(res*res) %p
    if bi[i]=="1":
      res=(res*a) %p
  return res
for k in range(K+1):
    ans += M * power_func(M-1,N-1-k,MOD) * NcK[k]
    ans %= MOD
print(ans)

Fixed submission:
#互いに素なa,bについて、a*x+b*y=1の一つの解
def extgcd(a,b):
    r = [1,0,a]
    w = [0,1,b]
    while w[2]!=1:
        q = r[2]//w[2]
        r2 = w
        w2 = [r[0]-q*w[0],r[1]-q*w[1],r[2]-q*w[2]]
        r = r2
        w = w2
    #[x,y]
    return [w[0],w[1]]

# aの逆元(mod m)を求める。(aとmは互いに素であることが前提)
def mod_inv(a,m):
    x = extgcd(a,m)[0]
    return (m+x%m)%m

import math
MOD = 998244353
N,M,K = [int(hoge) for hoge in input().split()]
NcK = []
POWER = []
cur = 1#Nc0
for k in range(K+1):
    NcK.append(cur)
    cur *= (N-1-k)* mod_inv(k+1,MOD)
    cur %= MOD    

ans = 0
Power = 1
for k in range(N-1-K):#M-1**n-1-K
    Power *= M-1
    Power %= MOD

for k in range(K,-1,-1):
    ans += Power * NcK[k]
        #M-1 ** N-1-k ということは…？
    if k:
        Power *= M-1
        Power %= MOD
    

print((M*ans)%MOD)