#include<bits/stdc++.h> using namespace std; #define int long long #define pii pair<int,int> #define fr first #define sc second #define mk make_pair #define inx(u) int I=h[(u)],v=edge[I].v;I;I=edge[I].nx,v=edge[I].v int read(){int x=0,f=1;char c=getchar();while(c<'0'||c>'9'){if(c=='-')f=-1;c=getchar();}while(c>='0'&&c<='9')x=x*10+c-'0',c=getchar();return x*f;} const int MAXN=510,V=500,Mod=998244353; struct Edge{int v,nx;}edge[MAXN<<1];int h[MAXN],CNT=1;void add_side(int u,int v){edge[++CNT]={v,h[u]};h[u]=CNT;edge[++CNT]={u,h[v]};h[v]=CNT;} int n,ans,a[MAXN],p[MAXN],f[MAXN][2]; void slv(){ n=read(); for(int i=1;i<=n;i++)a[read()]=1; for(int lim=0;lim<=V;lim++){ memset(f,0,sizeof(f)); f[V][a[lim]]=1; for(int i=V;i>lim;i--){ if(a[i]){ for(int s=0;s<2;s++) for(int j=i;j>lim&&i-j+1<=lim+1&&j*2>i;j--){ f[j-1][s|(i-j+1==lim+1)]+=f[i][s]; f[j-1][s|(i-j+1==lim+1)]%=Mod; } } else f[i-1][0]=(f[i-1][0]+f[i][0])%Mod,f[i-1][1]=(f[i-1][1]+f[i][1])%Mod; } ans+=f[lim][1]; ans%=Mod; } printf("%lld",ans); } signed main(){ slv(); return 0; }