For example, the word debacle would work because of debac, but seabed would not work because: 1. there is no c in any 5-character sequence tha
#! perl -lw for (qw(debacle seabed feedback)) { print if /([a-e])(?!\1) ([a-e])(?!\1)(?!\2) ([a-e])(?!\1)(?!\2)(?!\3) ([a-e])(?!\1)(?!\2)(?!\3)(?!\4) ([a-e])/x; }