Doesn't accept the list index?

Doesn't accept the list index?

I have this peice of code:
n = int (input ('Enter the Number of Players: '))
m = [[j] for j in range (0, n)]
all_names= []
i = 0
while n > 1:
m[i] = input('Player {0}: '.format (i+1))
all_names.extend ([m[i]])
if m[i][0] != m[i-1][-1]:
b= m.pop (i)
n = n-1
if all_names.count (m[i]) == 2:
n = n-1
b= m.pop (i)
i = i+1
It says the index is out of range (second if clause) but I dont get it, why?