modint 封装

struct modint{
	int x;
	static int Mod;
	static void setmod(int _){Mod=_;}
	static int getmod(){return Mod;}
	int qpow(int b,int p){
		if(!p) return 1;
		int d=qpow(b,p>>1);
		if(p&1) return 1ll*d*d%Mod*b%Mod;
		else return 1ll*d*d%Mod;
	}
	modint(int o=0){x=o;}
	modint &operator=(int o){return x=o,*this;}
	modint &operator+=(modint o){return x=x+o.x>=Mod?x+o.x-Mod:x+o.x,*this;}
	modint &operator-=(modint o){return x=(x>=o.x?x-o.x:x-o.x+Mod),*this;}
	modint &operator*=(modint o){return x=1ll*x*o.x%Mod,*this;}
	modint &operator^=(modint o){return x=qpow(x,o.x),*this;}
	modint &operator/=(modint o){return *this*=(o^=(Mod-2));}
	modint &operator++() & {return (*this)+=1;}
	modint &operator--() & {return (*this)-=1;}
	modint &operator++(int) & {
		modint temp=*this;
		(*this)+=1;
		return temp;
	}
	modint &operator--(int) & {
		modint temp=*this;
		(*this)-=1;
		return temp;
	}
	friend modint operator+(modint a,modint b){return a+=b;}
	friend modint operator-(modint a,modint b){return a-=b;}
	friend modint operator*(modint a,modint b){return a*=b;}
	friend modint operator/(modint a,modint b){return a/=b;}
	friend modint operator^(modint a,modint b){return a^=b;}
	friend bool operator==(modint a,modint b){return a.x==b.x;}
	friend bool operator!=(modint a,modint b){return a.x!=b.x;}
	bool operator<(const modint &b) const{return x<b.x;}
	bool operator>(const modint &b) const{return x>b.x;}
	bool operator<=(const modint &b) const{return x<b.x||x==b.x;}
	bool operator>=(const modint &b) const{return x>b.x||x==b.x;}
	bool operator!(){return !x;}
	modint operator-(){return x?Mod-x:0;};
	friend std::istream &operator>>(std::istream &is,modint &k) {
		int val;
		is>>val;
		k=val;
		return is;
	}
	friend std::ostream &operator<<(std::ostream &os,modint k){return os<<k.x;}
};
int modint::Mod=998244353;