import std.conv, std.functional, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.container, std.math, std.numeric, std.range, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }


enum INF = 10L^^18;

int N;
long[] B;

void main() {
  try {
    for (; ; ) {
      N = readInt();
      B = new long[N];
      foreach (i; 0 .. N) {
        B[i] = readLong();
      }
      
      // a[i] = p[i] a[0] + q[i]
      auto p = new long[N + 1];
      auto q = new long[N + 1];
      p[0] = 1;
      q[0] = 0;
      foreach (i; 0 .. N) {
        if (i % 2 == 0) {
          p[i + 1] = -p[i];
          q[i + 1] = B[i] - q[i];
        } else {
          p[i + 1] = p[i];
          q[i + 1] = q[i] - B[i];
        }
      }
      
      long lb = -INF, ub = +INF;
      foreach (i; 0 .. N + 1) {
        switch (p[i]) {
          case +1: {
            // a[0] + q[i] >= 1
            chmax(lb, 1 - q[i]);
          } break;
          case -1: {
            // -a[0] + q[i] >= 1
            chmin(ub, q[i] - 1);
          } break;
          default: assert(false);
        }
      }
      if (lb <= ub) {
        writeln(N + 1);
        foreach (i; 0 .. N + 1) {
          writeln(p[i] * lb + q[i]);
        }
      } else {
        writeln(-1);
      }
    }
  } catch (EOFException e) {
  }
}