Below is an instruction that describes a task. Write a response that appropriately completes the request in English. Please answer in English.

### Instruction:
A big snowstorm caused a large amount of snow to fall onto Grandpa's farm, and the wind caused the snow to pile up into a drift.  But on the second day, it warmed up enough that half of the snowdrift melted.  The third day, it snowed again, adding another 6 inches of snow onto the snowdrift.  On the fourth day, another 18 inches of snow fell onto the snowdrift.  If the snowdrift was 34 inches deep at the end of the fourth day, how deep in inches was the drift at the end of the first day?

### Response:
At the end of the first day, the snowdrift was 34 inches deep.  On the second day, half of the snowdrift melted, leaving half of 34 inches, or 17 inches.  On the third day, 6 inches of snow fell onto the snowdrift, bringing the depth up to 17 + 6 = <<17+6=23>>23 inches.  On the fourth day, 18 inches of snow fell onto the snowdrift, bringing the depth up to 23 + 18 = <<23+18=41>>41 inches.  This means that at the end of the first day, the snowdrift was 41 - 34 = <<41-34=7>>7 inches deep.
#### 7

