#include <bits/stdc++.h>
using namespace std;
#define For(Ti,Ta,Tb) for(auto Ti=(Ta);Ti<=(Tb);++Ti)
#define Dec(Ti,Ta,Tb) for(auto Ti=(Ta);Ti>=(Tb);--Ti)
#define debug(...) fprintf(stderr,__VA_ARGS__)
#define range(Tx) begin(Tx),end(Tx)
using ll=long long;
const int M=1e7+5,Mod=998244353;
int m,l,r,cnt;
char s[M];
ll sum(ll x){
	x%=Mod;
	return (x+1)*x/2%Mod;
}
int main(){
	cin.tie(nullptr)->sync_with_stdio(false);
	cin>>m>>l>>r>>cnt>>(s+1);
	ll n=m*cnt;
	For(i,1,m){
		n+=s[i]-'0';
	}
	ll ans=1;
	For(i,1,m){
		(ans*=233)%=Mod;
	}
	cout<<ans*sum(n-m+1)%Mod<<'\n';
	return 0;
}