letter(s;e;n;d;m;o;r;y).
#hide letter/1.

$domain(0..9).

X $!= Y :- letter(X;Y), X != Y.

s*1000+e*100+n*10+d + m*1000+o*100+r*10+e $== m*10000+o*1000+n*100+e*10+y.

m $== 1.
s $> 0.