# Sum of negatives

Given a stream of numbers, your task is to calculate the sum up until the first non-negative number. All the numbers after the first non-negative one should be ignored.

It’s guaranteed that the input contains at least a single non-negative number. If the first number is non-negative, the program should print 0.

The program should print the required sum.

Input | Output |

-20
-3
-2
-30
0
-1 | -55 |

**Explanation**: The first non-negative number in the list

`-20, -3, -2, -30, 0, -1`

is `0`

. So, we should calculate the sum of numbers before `0`

. This results in `-20 -3 -2 -30 = -55`

.#### Constraints

Time limit: 1 seconds

Memory limit: 512 MB

Output limit: 1 MB