The ornamental design for a watch, as shown and described.
1.-6. Watches
1.1 : Front
1.2 : Perspective
2.1 : Front
2.2 : Perspective
3.1 : Front
3.2 : Perspective
4.1 : Front
4.2 : Perspective
5.1 : Front
5.2 : Perspective
6.1 : Front
6.2 : Perspective
The broken line showing of a watchband and stitching is included for the purpose of illustrating portions of the watch and forms no part of the claimed design.