Revert "Laba4"

This reverts commit f115d8275c27deedc1dd9f87ac521c4acaa021dc.
Revert "laba6"

This reverts commit f84dfc1307d4e2c1d83645bdddb1832f5cb61cf7.
Revert "laba5 variant 1"

This reverts commit 027296799e0bd0cd14cec14650e58c0857292c6b.