import re

pattern = re.compile("^([0-9]+)+$")

content  = "s23434"

if(pattern.match(content)):
    print(pattern.match(content).pos)
else:
    print('not matched')

not matched

content  = "23434"

if(pattern.match(content)):
    print('matched at : ', pattern.match(content).pos)
else:
    print('not matched')

matched at :  0