IndexError: list index out of range

[abdullahali]

N = 3

# Returns true if square is magic
# square, else returns false.
def is_magic(square):
    # calculate the sum of
    # the prime diagonal
    sum = 0
    for i in range(0, N):
        sum += square[i][i]

        # For sums of Rows
    for i in range(0, N):
        rowSum = 0
        for j in range(0, N):
            rowSum += square[i][j]

            # check if every row sum is
        # equal to prime diagonal sum
        if (rowSum != sum):
            return False

    # For sums of Columns
    for i in range(0, N):
        columnSum = 0
        for j in range(0, N):
            columnSum += square[j][i]

            # check if every column sum is
        # equal to prime diagonal sum
        if (sum != columnSum):
            return False

    return True

str_input = input("write a squence of nine numbers")
str_list = str_input.split()

square = []
for i in range(0, N):
    square.append([])
    for j in range(0, N):
        square[i].append(int(str_list[j + i * N]))

if (is_magic(str_list)):
    print("This is Magic Square")
else:
    print("This is Not a magic Square")

The error I keep getting is in the line where it says
square[i].append(int(str_list[j + i * N]))

I am trying to create a program that asks user for sequence of 9 numbers and determines if they are nagic square or not.