朴素代码

#include<bits/stdc++.h>
#define int unsigned long long
using namespace std;
const int md=998244353;
int ans,a,b,k;
signed main(){
	ans=1;
	cin>>a>>b>>k;
	for(int i=1;i<=k;i++){
		if(i%a==0&&i%b)ans=ans*2%md;
		if(i%b==0&&i%a){
			if(ans&1)ans++;
			ans=ans*499122177%md;
		}
	}
	printf("%lld",ans);
	return 0;
}