from collections import defaultdict
N,A,K=list(map(int,input().split()))
C=defaultdict(int)

def C_Num(N,A):
	for i in range(1,N+1):
		C[i]=A*i

C_Num(N,A)
ans=0
MOD=998244353

def Remove1(K):
	cnt=0
	for i in range(1,N+1):
		M=C[i]//K
		cnt=(cnt+M*i)%MOD
		C[i]=C[i]%K
	return cnt

ans=Remove1(K)

def Remove2(K):
	cnt=0
	now=0
	ok=0
	for i in range(N,0,-1):
		if ok==0 and C[i]!=0:
			cnt+=i
			ok=1
			now=C[i]
		elif ok==1:
			now+=C[i]
			if now>K:
				now-=K
				cnt+=i
	return cnt%MOD
ans=(ans+Remove2(K))%MOD
print((ans*2)%MOD)