See if you can figure out what this letter string is.

A letter string is a series of letters in a particular order. For example, bdaec.

The string has 7 letters and uses the letters x, y, z, and w. w and x each appear once, y appears twice, and z appears thrice. Using the following four hints, can you figure out the string?

1. Each z has a w immediately on its left.

2. The letter on the left end and the letter on the right end are different from each other, and neither of them are x.

3. Neither the 3rd letter from the left nor the 2nd letter from the right are w.

4. The 2nd letter from the right and the 2nd letter from the left are the same as each other.