#line 1 "a.cpp"
#include<iostream>
using namespace std;
#line 3 "/home/kotatsugame/library/math/modint.cpp"
#include<utility>
template<int m>
struct modint{
	unsigned int x;
	constexpr modint()noexcept:x(){}
	constexpr modint(long long _x)noexcept:x((_x%=m)<0?_x+m:_x){}
	constexpr unsigned int val()const noexcept{return x;}
	constexpr modint&operator++()noexcept{if(++x==m)x=0;return*this;}
	constexpr modint&operator--()noexcept{if(x==0)x=m;--x;return*this;}
	constexpr modint operator++(int)noexcept{modint res=*this;++*this;return res;}
	constexpr modint operator--(int)noexcept{modint res=*this;--*this;return res;}
	constexpr modint&operator+=(const modint&a)noexcept{x+=a.x;if(x>=m)x-=m;return*this;}
	constexpr modint&operator-=(const modint&a)noexcept{if(x<a.x)x+=m;x-=a.x;return*this;}
	constexpr modint&operator*=(const modint&a)noexcept{x=(unsigned long long)x*a.x%m;return*this;}
	constexpr modint&operator/=(const modint&a)noexcept{return*this*=a.inv();}
	constexpr modint operator+()const noexcept{return*this;}
	constexpr modint operator-()const noexcept{return modint()-*this;}
	constexpr modint pow(long long n)const noexcept
	{
		if(n<0)return pow(-n).inv();
		modint x=*this,r=1;
		for(;n;x*=x,n>>=1)if(n&1)r*=x;
		return r;
	}
	constexpr modint inv()const noexcept
	{
		int s=x,t=m,x=1,u=0;
		while(t)
		{
			int k=s/t;
			s-=k*t;
			swap(s,t);
			x-=k*u;
			swap(x,u);
		}
		return modint(x);
	}
	constexpr modint operator+(const modint&a)const noexcept{return modint(*this)+=a;}
	constexpr modint operator-(const modint&a)const noexcept{return modint(*this)-=a;}
	constexpr modint operator*(const modint&a)const noexcept{return modint(*this)*=a;}
	constexpr modint operator/(const modint&a)const noexcept{return modint(*this)/=a;}
	constexpr bool operator==(const modint&a)const noexcept{return x==a.x;}
	constexpr bool operator!=(const modint&a)const noexcept{return x!=a.x;}
	friend ostream&operator<<(ostream&os,const modint&a){return os<<a.x;}
	friend istream&operator>>(istream&is,modint&a){long long v;is>>v;a=modint(v);return is;}
};
#line 4 "a.cpp"
using mint=modint<998244353>;
int N,M,A,B;
mint fac[4<<17],inv[4<<17];
mint comb(int a,int b){return fac[a]*inv[b]*inv[a-b];}
main()
{
	cin>>N>>M>>A>>B;
	fac[0]=1;
	for(int i=1;i<4<<17;i++)fac[i]=fac[i-1]*i;
	inv[(4<<17)-1]=fac[(4<<17)-1].inv();
	for(int i=(4<<17)-1;i--;)inv[i]=inv[i+1]*(i+1);
	if((long)(N-1)*A>B)
	{
		cout<<0<<endl;
		return 0;
	}
	int T=B-(long)(N-1)*A;
	mint ans=0;
	for(int i=0;i<=T;i++)
	{
		ans+=comb(N-1+i,N-1)*(T-i+1);
	}
	for(int i=1;i<=N;i++)ans*=i;
	cout<<ans<<endl;
}