Regarding question- Simple input

Greetings of the day!!
In this question, the no of input to be taken by the programmer is not stated.

#include
using namespace std;
int main() {

int x=0,a;
while(x>=0)
{
	cin>>a;
	x=x+a;
	cout<<a<<"\n";
}
return 0;

}
What is the error???