#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define IOS ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
const int maxx = 505;
vector <int> ach[maxx*4];
bitset<maxx*maxx> pos[maxx*4];
//node tr[maxx*4];
bitset <maxx*maxx> out[maxx];
void update(int l, int r, int tl, int tr, int id, int val){
// cout << tl << " " << tr << " " << val << " done\n";
if(l > tr || r < tl)
return;
if(l >= tl && r <= tr){
ach[id].push_back(val);
// cout << "added " << l << " " << r << " " << id << "\n";
return;
}
int m = (l + r) / 2;
update(l, m, tl, tr, id+id, val);
update(m+1, r, tl ,tr, id+id+1, val);
// cout << "finally\n";
}
void build(int l, int r, int id){
pos[id][0] = 1;
for(auto it : ach[id])
pos[id] |= (pos[id] << it);
if(l == r){
out[l] = pos[id];
return;
}
int m = (l + r) / 2;
pos[id+id] = pos[id];
pos[id+id+1] = pos[id];
build(l, m, id+id);
build(m+1, r, id+id+1);
}
void S()
{
int n;
cin >> n;
vector <int> a(n+1);
int s = 0;
for(int i = 1; i <= n; i ++){
cin >> a[i];
s += a[i];
}
if(s % 2 == 1){
cout << 0;
return;
}
for(int i = 1; i <= n; i ++){
update(1, n+1, 1, i-1, 1, a[i]);
update(1, n+1, i+1, n+1, 1, a[i]);
}
// cout << s;/*
build(1, n+1, 1);
if(out[n+1][s/2] == 0){
cout << 0;
return;
}
vector <int> ans;
for(int can = 1; can <= s; can ++){
bool ok = 1;
for(int i = 1; i <= n; i ++){
int s1 = s - a[i] + can;
if(s1 % 2 == 1 || out[i][s1/2] == 0){
ok = 0;
break;
}
}
if(ok)
ans.push_back(can);
}
cout << ans.size() << "\n";
for(auto it : ans)
cout << it << " ";
}
int main()
{
IOS;
/*int t;
cin >> t;
while(t --)*/
S();
}
