2 3 6 5 Overline 4 3

2 – [3 – {6 – (5 – )}]

2 – [3 – {6 – (5 – $\overline { 4 -3 }$ )}]
⇒ 2 – [3 – {6 – (5 – 1)}]
⇒ 2 – [3 – {6 – 4}]
⇒ 2 – (3 – 2)
⇒ 2 – 1 = 1