P781 xx | | —c — | — @pq | > || —c G 4 — xp | > || —A÷ — > —— x > | —c cP781 p | > |= —c — > —c xx | > || —c — — — > — | —c xq | > | —GcP781 — p | > || —c | — xp | > || —c G | — — x | |= —GP781 ÷ pq | > || —c G > — xq | > || —c G | — pq x | | —cc—