I am super new at Python and I am facing a problem when converting a nested list to a list of integer only.

I have this type of nested list in which all sub-list contains strings (digit and char)

```
lists = [['1', '2', '0', 'a', 'b'], ['3', '2', '1'], ['1','5', '5']]

```

I want to convert the digits to integer, and also put the char in one list. The output that I want is something like this

```
`new_lists = [[1, 2, 0, 'a', 'b'], [3, 2, 1], [1, 5, 5]]`

```

What would i do is something like this

```
for item in lists:
new_list=[]
if (in the first list item can be converted to integer):
    new_list.append(int(item))
else:
  new_list.append(item)

```

How the string can be converted to an integer? Or is there any better way to do it?
Thanks in advance