sort(1) puzzle #1

(I’m waiting for a build to finish, so here’s a small Solaris sort(1) trick.)

Question: I have the following data file

1401 8192
1401 3487
1401 0807
1305 3471
1305 6565
1408 2312
1408 1233

Using only sort(1), how do I generate a file sorted by the first field, with only the highest valued second field for each first field value?

Note that the unique line behaviour of sort(1) isn’t well specified, so versions from other platforms may not be able to do this trick.