"ABCDCABDACDBDACBBCDAACBDADCBCDABDABCBCADCADBCDBACBADABDCADBCBDCADCBABACDBADCBDACCBDADBCADCAB"→Str0
"ABCD"→Str1
length(Str0)→L
[[0,0,0,0][0,0,0,0][0,0,0,0][0,0,0,0]]→[A]

For(I,1,L,4)
For(J,1,4,1)
sub(Str0,I+J-1,1)→Str2
For(K,1,4,1)
sub(Str1,K,1)→Str3
If Str2=Str3
Then
[A](J,K)+1→[A](J,K)
End
End
End
End

Matr►list([A],1,L₁)
min(L₁)→M

" "→Str4

For(I,1,4,1)
For(J,1,4,1)
If [A](I,J)=M
Then
Str4+sub(Str1,J,1)→Str4
End
End
End
sub(Str4,2,4)→Str4
Disp "MISSING"
Disp Str4