#include<bits/stdc++.h>

using namespace std;
typedef unsigned int uint;
typedef long long int ll;
typedef unsigned long long int ull;

#define debugv(v) printf("L%d %s => ",__LINE__,#v);for(auto e:v){cout<<e<<" ";}cout<<endl;
#define debugm(m) printf("L%d %s is..\n",__LINE__,#m);for(auto v:m){for(auto e:v){cout<<e<<" ";}cout<<endl;}
#define debuga(m,w) printf("L%d %s is => ",__LINE__,#m);for(int x=0;x<(w);x++){cout<<(m)[x]<<" ";}cout<<endl;
#define debugaa(m,w,h) printf("L%d %s is..\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){cout<<(m)[x][y]<<" ";}cout<<endl;}
#define ALL(v) (v).begin(),(v).end()
#define BIGINT 0x7FFFFFFF
#define E107 1000000007
void printbit(int u){if(u==0)cout<<0;else{int s=0,k=0;for(;0<u;u>>=1,k++)s=(s<<1)|(u&1);for(;0<k--;s>>=1)cout<<(s&1);}}

#define TIME chrono::system_clock::now()
#define MILLISEC(t) (chrono::duration_cast<chrono::milliseconds>(t).count())

template<typename T1,typename T2>
ostream& operator <<(ostream &o,const pair<T1,T2> p){o<<"("<<p.first<<":"<<p.second<<")";return o;}

int width,height;
int m,n;

random_device noize;   // noize
mt19937 mt(noize());   // 32ビット版のメルセンヌ・ツイスター
// mt19937_64 mt64;    // 64ビット版のメルセンヌ・ツイスター

int rand_int(int l,int h){
    uniform_int_distribution<> range(l,h);
    return range(mt);
}

ll data[100010];

ll result[100010];

void fail(){
    cout << -1 << endl;
    exit(0);
}

int main(){
    int i,j,k;
    ll x,y,a,b;
    
    cin >> n;
    
    b = 0;
    for (i=0;i<n;i++){
        scanf("%lld",&a);
        data[i]=a;
        //b = max(data[i],b);
    }
    
    if (data[0]<=1){
        fail();
    }
    
    ll low,high,mid;
    
    low = 1;
    high = 1e18;
    
    for (i=0;i<n;i++){
        if (i%2 == 0){
            a = max(data[i] - high,1ll);
            b = data[i] - low;
            low = a;
            high = b;
        }else{
            a = max(low - data[i],1ll);
            b = high - data[i];
            low = a;
            high = b;
        }
        if (low > high){
            fail();
        }
    }
    
    //printf("low:%lld high:%lld\n",low,high);cout.flush();
    
    b = low;
    result[n] = b;
    for (i=n-1;0<=i;i--){
        if (i%2==0){
            b = result[i] = (data[i]-b);
        }else{
            b = result[i] = (b+data[i]);
        }
        //cout<<b<<endl;
        if (b<=0 || 1000000000000000000<b){
            cout << ":(" << endl;
            abort();
        }
    }
    
    cout << (n+1) << endl;
    for (i=0;i<=n;i++){
        cout << result[i] << endl;
    }
    
    return 0;
}