# Adding M0, M1, … Mn between each two elements in a list

I would like to loop through a list, which is called output as shown below:

```output = [0, 1, 2, 3, 4, 5, 6]
```

But I have to exclude the first and last elements `[1, 2, 3, 4, 5]`

Then I would like to add between each two elements M. For the first two elements M0, the second two elements M1 and so on.

x= `[1, M0, 2, M1, 3, M2, 4, M3, 5]`

The expected output =

```[[1, M0, 2],[2, M1, 3],[3, M2, 4],[4, M3, 5]]
```

And could I solve it with (while, for, and if) instead of using multiple for loops? Could you please assist me?

Below is my try:

# Python code:

```output = [0, 1, 2, 3, 4, 5, 6]

Total = []
for i in output:
if i != output and i != output[-1]:
Total.append(i)
print(Total)
for j in (Total):
print(j)

h = []
for x in Total:
for y in (x,'M'0):
h.append(y)
print(h)
```

Here is a solution you can try, using `zip` to create pairs & `enumerate` over that.

```output = [0, 1, 2, 3, 4, 5, 6]

output = output[1:-1] # Remove first & last digit

print(
[[i, f'M{index}', j] for index, (i, j) in enumerate(zip(output, output[1:]))]
)
```

```[[1, 'M0', 2], [2, 'M1', 3], [3, 'M2', 4], [4, 'M3', 5]]
```