#include "bits/stdc++.h"
#define MAXN 100009
#define INF 1000000007
#define mp(x,y) make_pair(x,y)
#define all(v) v.begin(),v.end()
#define pb(x) push_back(x)
#define wr cout<<"----------------"<<endl;
#define ppb() pop_back()
#define tr(ii,c) for(__typeof((c).begin()) ii=(c).begin();ii!=(c).end();ii++)
#define ff first
#define ss second
#define my_little_dodge 46
#define debug(x) cerr<< #x <<" = "<< x<<endl;
using namespace std;
typedef long long ll;
typedef pair<int,int> PII;
template<class T>bool umin(T& a,T b){if(a>b){a=b;return 1;}return 0;}
template<class T>bool umax(T& a,T b){if(a<b){a=b;return 1;}return 0;}
const int N=505;
bitset<N*N>dp;
int arr[N],vis[N];
bool ans[N*N];
vector<int>s[N*4];
int n,sum,total;
void upd(int l,int r,int v,int nd,int x,int y){
if(l>y or x>r)
return;
if(l<=x and y<=r){
s[nd].pb(v);
return;
}
int mid=(x+y)>>1;
upd(l,r,v,nd<<1,x,mid);
upd(l,r,v,nd<<1|1,mid+1,y);
}
void solve(int nd,int x,int y,bitset<N*N>tmp){
tr(it,s[nd])
tmp=tmp|(tmp<<(*it));
if(x==y){
if(vis[arr[x]])
return;
vis[arr[x]]=1;
total-=arr[x];
for(int j=0;j<=sum;j++){
if(!ans[j])
continue;
if((j+total)&1){
ans[j]=0;
continue;
}
if(!tmp[(j+total)/2]){
ans[j]=0;
continue;
}
}
total+=arr[x];
return;
}
int mid=(x+y)>>1;
solve(nd<<1,x,mid,tmp);
solve(nd<<1|1,mid+1,y,tmp);
}
int main(){
//~ freopen("file.in", "r", stdin);
scanf("%d",&n);
dp[0]=1;
for(int i=1;i<=n;i++){
scanf("%d",arr+i);
dp=dp|(dp<<arr[i]);
upd(1,i-1,arr[i],1,1,n);
upd(i+1,n,arr[i],1,1,n);
sum+=arr[i];
}
if(sum&1 or !dp[sum/2]){
puts("0");
return 0;
}
for(int j=0;j<=sum;j++)
ans[j]=1;
total=sum;
dp.reset();dp[0]=1;
solve(1,1,n,dp);
int res=0;
for(int j=0;j<=sum;j++)
res+=ans[j];
printf("%d\n",res);
for(int j=0;j<=sum;j++)
if(ans[j])
printf("%d ",j);
puts("");
return 0;
}
