#include<bits/stdc++.h>
#include<atcoder/modint>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef long double ldb;

#define rep(i,l,r) for(int i(l);i<=(r);++i)
#define per(i,r,l) for(int i(r);i>=(l);--i)
#define eb emplace_back
#define File(filename) freopen(filename ".in","r",stdin),freopen(filename ".out","w",stdout)

#ifdef EXODUS
	#define Debug(...) fprintf(stderr,__VA_ARGS__)
#else
	#define Debug(...) 0
#endif

//=========================================================================================================
// Something about IO

template<typename T>
void read(T &x){
	x=0;T flg=1;
	char ch=getchar();
	while(!isdigit(ch)){if(ch=='-')flg=-1;ch=getchar();}
	while(isdigit(ch))x=(x<<3)+(x<<1)+(ch^48),ch=getchar();
	x*=flg;
}
template<typename T,typename... Args>
void read(T &x,Args &...args){read(x),read(args...);}

//=========================================================================================================
// Define the global variables here.

bool membg=0;

constexpr int N=1e6+7;
char s[N],t[N];
int n,m;


constexpr int mod=998244353,base=131;
struct Hash_t{
	pair<int,ull>val;
	Hash_t (int val1=0,ull val2=0ull):val(make_pair(val1,val2)){}
	Hash_t operator +(int rhs){return Hash_t(val.first+rhs%mod,val.second+rhs);}
	Hash_t operator -(Hash_t rhs){return Hash_t((val.first-rhs.val.first+mod)%mod,val.second-rhs.val.second);}
	Hash_t operator *(int rhs){return Hash_t((ll)val.first*rhs%mod,val.second*rhs);}
	Hash_t operator *(Hash_t rhs){return Hash_t((ll)val.first*rhs.val.first%mod,val.second*rhs.val.second);}
	bool operator ==(Hash_t rhs){return val==rhs.val;}
};

Hash_t hshs[N],hsht[N],pwr[N];

bool memed=0;

//=========================================================================================================
// Code here.

Hash_t ask(Hash_t *hsh,int l,int r){
	return hsh[r]-hsh[l-1]*pwr[r-l+1];
}

int getlcp(int begs,int begt){
	int l=1,r=n,len=0;
	while(l<=r){
		int mid=(l+r)>>1;
		if(begs+mid-1<=n&&begt+mid-1<=m&&ask(hshs,begs,begs+mid-1)==ask(hsht,begt,begt+mid-1))
			l=mid+1,len=mid;
		else r=mid-1;
	}
	return len;
}

int getpos(int begs){
	int begt=1;
	int res=getlcp(begs,begt);
	if(begs+res-1==n||begt+res-1==m)return begs+res-1;
	begs+=res;begt+=res;
	if(begs==n||begt==m)return begs;
	begs++,begt++;
	res=getlcp(begs,begt);
	return begs+res-1;
}

int f[N],g[N],h[N];
int sumf[N],sumg[N],sumh[N];

void solve(){
	scanf("%s%s",s+1,t+1);
	n=strlen(s+1),m=strlen(t+1);
	for(int i=1;i<=n;i++)hshs[i]=hshs[i-1]*base+s[i];
	for(int i=1;i<=m;i++)hsht[i]=hsht[i-1]*base+t[i];
	int len=max(n,m);
	pwr[0]=Hash_t(1,1);
	for(int i=1;i<=len;i++)pwr[i]=pwr[i-1]*base;
	f[n+1]=g[n+1]=0,h[n+1]=1;
	sumf[n+1]=0,sumg[n+1]=0,sumh[n+1]=1;
	for(int i=n;i>=1;i--){
		int R=getpos(i);
		int F=sumf[i+1]-sumf[R+2],G=sumg[i+1]-sumg[R+2],H=sumh[i+1]-sumh[R+2];
		f[i]=(F+(ll)2*G+H)%mod,g[i]=(G+H)%mod,h[i]=H;
		sumf[i]=sumf[i+1]+f[i],sumg[i]=sumg[i+1]+g[i],sumh[i]=sumh[i+1]+h[i];
	}
	printf("%d\n",f[1]);
	return;
}


//=========================================================================================================

int main(){
	Debug("%.3lfMB\n",fabs(&memed-&membg)/1024.0/1024.0);
	int timbg=clock();
	int T=1;
	while(T--)solve();
	int timed=clock();
	Debug("%.3lfs\n",1.0*(timed-timbg)/CLOCKS_PER_SEC);
	fflush(stdout);
	return 0;
}

answer.code:2:9: fatal error: atcoder/modint: No such file or directory
    2 | #include<atcoder/modint>
      |         ^~~~~~~~~~~~~~~~
compilation terminated.