My shortest solution…

from itertools import *
print(*list((len(list(g)), int(k)) for k, g in groupby(input())))

A solution without groupby()…

o = p = []
for c in map(int, input()):
  if c == p:
    n += 1
    continue
  o += [(n, p)] if p != [] else []
  p = c
  n = 1
print(*(o + [(n, p)]))