sub LCS$(a$, b$)
if len(a$) = 0 or len(b$) = 0 return
while len(b$)
for j = len(b$) to 1 step -1
if instr(a$, left$(b$, j)) return left$(b$, j)
next j
b$ = mid$(b$, 2)
wend
end sub
print LCS$("thisisatest", "testing123testing")
end