#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <iomanip>
#include <cassert>
using namespace std;

#define GET_ARG(a,b,c,F,...) F
#define REP3(i,s,e) for (i = s; i <= e; i++)
#define REP2(i,n) REP3 (i,0,(int)(n)-1)
#define REP(...) GET_ARG (__VA_ARGS__,REP3,REP2) (__VA_ARGS__)
#define RREP3(i,s,e) for (i = s; i >= e; i--)
#define RREP2(i,n) RREP3 (i,(int)(n)-1,0)
#define RREP(...) GET_ARG (__VA_ARGS__,RREP3,RREP2) (__VA_ARGS__)
#define DEBUG(x) cerr << #x ": " << x << endl

typedef long long ll;

ll b[100000];

int main(void) {
    int i, n;
    scanf("%d",&n);
    REP (i,n) scanf("%lld",&b[i]);

    ll l = 1, r = (ll)(1e18)+1;
    while (l + 1 < r) {
        ll m = (l + r) / 2;
        ll x = m;
        REP (i,n) {
            if (i % 2 == 0)
                x = b[i] - x;
            else
                x = x - b[i];
            if (x > 1e18) {
                l = m;
                break;
            }
            if (x <= 0) {
                r = m;
                break;
            }
        }
        if (i == n) {
            l = m;
            break;
        }
    }
    vector<ll> ans;
    ans.push_back(l);
    REP (i,n) {
        if (i % 2 == 0)
            l = b[i] - l;
        else
            l = l - b[i];
        if (l <= 0 || l > 1e18) break;
        ans.push_back(l);
    }
    if (ans.size() == n+1) {
        printf("%d\n",n+1);
        REP (i,n+1) printf("%lld\n",ans[i]);
    }
    else puts("-1");
    return 0;
}