#include "bits/stdc++.h"
using namespace std;
#define int long long
#define FOR(i, a, b) for(int i=(a);i<(b);i++)
#define RFOR(i, a, b) for(int i=(b-1);i>=(a);i--)
#define REP(i, n) for(int i=0; i<(n); i++)
#define RREP(i, n) for(int i=(n-1); i>=0; i--)
#define ALL(a) (a).begin(),(a).end()
#define UNIQUE_SORT(l) sort(ALL(l)); l.erase(unique(ALL(l)), l.end());
#define CONTAIN(a, b) find(ALL(a), (b)) != (a).end()
#define array2(type, x, y) array<array<type, y>, x>
#define vector2(type) vector<vector<type> >
#define out(...) printf(__VA_ARGS__)

int dxy[] = {0, 1, 0, -1, 0};

void solve();
signed main()
{
#if DEBUG
    std::ifstream in("input.txt");
    std::cin.rdbuf(in.rdbuf());
#endif
    cin.tie(0);
    ios::sync_with_stdio(false);
    solve();
    return 0;
}

/*================================*/

int N,M,Q;
int B[111111];
int A[111111];

// 下げるべき: -1, 上げるべき: 1, OK: 0
int check(int a) {
    A[0] = a;
    REP(i,N) {
        if (i%2) {
            A[i+1] = A[i] - B[i];
        } else {
            A[i+1] = B[i] - A[i];
        }
        if (A[i+1] < 0) return (i/2%2) ? 1 : -1;
    }
    return 0;
}

void printA() {
    cout << N+1 << endl;
    REP(i,N+1) out("%lld\n", A[i]);
}

void solve() {
    cin>>N;
    REP(i,N)cin>>B[i];
    
    int a0 = 0;
    RREP(i,30) {
        int ret = check(a0 + (1<<i));
        if (ret == 0) {
            printA();
            return;
        }
        if (ret == 1) {
            a0 += 1<<i;
        }
    }
    
    cout << -1 << endl;
}