include "pch.h"

include

using namespace std;

int main() {

int n;
int sum = 0;
while (cin>>n)
{
	if (n == 0) {
	
		break;
	}
	else if(n<0)
	{
		continue;
	}
	else
	{
		sum += n;
	}

}

cout << sum;

}