Why we are taking i-1 not i in this matrix chain multiplication p[i - 1] * p[k] * p[j]

#1

for (k = i; k < j; k++)
{
count = MatrixChainOrder(p, i, k) +
MatrixChainOrder(p, k + 1, j) +
p[i - 1] * p[k] * p[j];

    if (count < min) 
        min = count; 
} 

// Return minimum count 
return min;

}

#2

@rohitkandpal683
Can you please tell me the timestamp in the video lecture where this problem arise.

#3

i cannot uderstand from this vedio so i watch prateek bhaiya you tube vedio on matrix chain multiplication at 19.14 there is a loop k from i to j from there onwards i cannot understand how this loop and partition works https://www.youtube.com/watch?v=D1U74eFLg_g