PRINT FNlcs("1234", "1224533324")
      PRINT FNlcs("thisisatest", "testing123testing")
      END

      DEF FNlcs(a$, b$)
      IF a$="" OR b$="" THEN = ""
      IF RIGHT$(a$) = RIGHT$(b$) THEN = FNlcs(LEFT$(a$), LEFT$(b$)) + RIGHT$(a$)
      LOCAL x$, y$
      x$ = FNlcs(a$, LEFT$(b$))
      y$ = FNlcs(LEFT$(a$), b$)
      IF LEN(y$) > LEN(x$) SWAP x$,y$
      = x$