Sum of Negative Integers

Create a function that takes a string containing integers as well as other characters and return the sum of the negative integers only.

Examples

negative_sum("-12 13%14&-11") ➞ -23
# -12 + -11 = -23

negative_sum("22 13%14&-11-22 13 12") ➞ -33
# -11 + -22 = -33

Notes

There is at least one negative integer.