After feeling like you've been falling for a few minutes, you look at the device's tiny screen. "Error: Device must be calibrated before first use. Frequency drift detected. Cannot maintain destination lock." Below the message, the device shows a sequence of changes in frequency (your puzzle input). A value like +6 means the current frequency increases by 6; a value like -3 means the current frequency decreases by 3.

For example, if the device displays frequency changes of +1, -2, +3, +1, then starting from a frequency of zero, the following changes would occur:

Current frequency  0, change of +1; resulting frequency  1.
Current frequency  1, change of -2; resulting frequency -1.
Current frequency -1, change of +3; resulting frequency  2.
Current frequency  2, change of +1; resulting frequency  3.
In this example, the resulting frequency is 3.

Here are other example situations:

+1, +1, +1 results in  3
+1, +1, -2 results in  0
-1, -2, -3 results in -6
Starting with a frequency of zero, what is the resulting frequency after all of the changes in frequency have been applied?