int main(){
int n,a[100001],i;
scanf("%d",&n);
for(i=0;~scanf("%d",a+i);i++);
for(;n>2;n--)a[n-2]+=a[n];
if(a[2])printf("2\n%d %d %d",*a,a[1],a[2]);
else if(a[1])printf("1\n%d %d",*a,a[1]);
else if(a[0])printf("0\n%d",*a);
else puts("0\n0");
return 0;
}