C. Beautiful Triple Pairs

Polycarp was given an array 𝑎 of 𝑛 integers. He really likes triples of numbers, so for each 𝑗 (1≤𝑗≤𝑛−2) he wrote down a triple of elements [𝑎𝑗,𝑎𝑗+1,𝑎𝑗+2].

Polycarp considers a pair of triples 𝑏 and 𝑐 beautiful if they differ in exactly one position, that is, one of the following conditions is satisfied:

• 𝑏1≠𝑐1 and 𝑏2=𝑐2 and 𝑏3=𝑐3;
• 𝑏1=𝑐1 and 𝑏2≠𝑐2 and 𝑏3=𝑐3;
• 𝑏1=𝑐1 and 𝑏2=𝑐2 and 𝑏3≠𝑐3.

Find the number of beautiful pairs of triples among the written triples [𝑎𝑗,𝑎𝑗+1,𝑎𝑗+2].