How can i do a code in python3 that deletes only letters(with def)

Question

exemple
input:
avrvt25gsv57
output:
2557

Answer 1

inp='avrvt25gsv57'
print(*[i for i in inp if i.isdigit()],sep='')

#if you want to do it with def.
def removeLetters(s):
return ''.join([i for i in s if i.isdigit()])

print(removeLetters(inp))

Answer 2

https://code.sololearn.com/cXUSCYtqZbwJ/?ref=app