# import sys
# limit_number = 2000000
# sys.setrecursionlimit(limit_number)
#
#
# def f(b1, t1, p):
# b = b1
# t = t1
# global d
# while b < t:
# if 0 <= b - 1 < n - 1 and d[b - 1] > d[b]:
# tt = d[b]
# d[b] = d[b - 1]
# d[b - 1] = tt
# if 0 < t + 1 < n and d[t] > d[t + 1]:
# tt = d[t]
# d[t] = d[t + 1]
# d[t + 1] = tt
# if d[b] <= d[p] <= d[t]:
# t = t - 1
# b = b + 1
# elif d[t] <= d[p] <= d[b]:
# tt = d[t]
# d[t] = d[b]
# d[b] = tt
# t = t - 1
# b = b + 1
# elif d[t] <= d[p]:
# b = b + 1
# else:
# t = t - 1
#
# if 0 <= b - 1 < n - 1 and d[b - 1] > d[b]:
# tt = d[b]
# d[b] = d[b - 1]
# d[b - 1] = tt
# if 0 < t + 1 < n and d[t] > d[t + 1]:
# tt = d[t]
# d[t] = d[t + 1]
# d[t + 1] = tt
#
# if d[t] < d[p]:
# kk = d[p]
# d[p] = d[t]
# d[t] = kk
# else:
# for i in range(t - 1, p, -1):
# if d[i] < d[p]:
# kk = d[i]
# d[i] = d[p]
# d[p] = kk
# break
# if p + 1 < n and d[p + 1] < d[p]:
# qw = d[p]
# d[p] = d[p + 1]
# d[p + 1] = qw
# if b1 < b - 1:
# if b == b1 + 2 and d[b1] < d[b - 1]:
# u = 0
# else:
# f(b1, b - 1, b1 - 1)
# if t + 1 < t1:
# if t1 == t + 2 and d[t + 1] < d[t1]:
# u = 0
# else:
# f(t + 1, t1, t)
#
#
# n = int(input())
# k =
# d = list(map(int, input().split()))
#
# import copy
#
# k = copy.deepcopy(d)
#
# d.sort()
#
# for i in range(n):
# for j in range(n):
# if k[i] == d[j]:
# print(j, end=' ')
#
# n = int(input())
# d = list(map(int, input().split()))
#
# for i in range(n + 1):
# k = 0
# for j in range(0, n - 1, 1):
# if d[j] > d[j + 1]:
# k = 1
# break
# if k == 0:
# print(i)
# break
# for j in range(0, n - 1 - i, 1):
# if d[j] > d[j + 1]:
# t = d[j + 1]
# d[j + 1] = d[j]
# d[j] = t
# import sys
# limit_number = 2000000000
# sys.setrecursionlimit(limit_number)
#
#
# def f(n, k):
# global me
# if n == 1:
# return 1
# if k == 1:
# me[k] = n
# return n
# if me[k] != 0:
# return me[k]
# if k % 2 == 0:
# me[k] = (f(n, k // 2) * f(n, k // 2)) % 1000000007
# return me[k]
# else:
# me[k] = (n f(n, k // 2) f(n, k // 2)) % 1000000007
# return me[k]
#
#
# n, k = map(int, input().split())
# me = [0] * (k + 1)
# print(f(n, k))
# import sys
# limit_number = 2000000000
# sys.setrecursionlimit(limit_number)
#
#
# def f(n, r):
# if r == 1:
# return n
# return n * f(n - 1, r - 1)
#
#
# def g(r):
# if r == 1:
# return 1
# return r * g(r - 1)
#
#
# n, r = map(int, input().split())
# if r > n // 2:
# r = n - r
#
# x = f(n, r)
# x = (x // g(r)) % 1999
# print(x)
a, b, k = map(int, input().split())
c = 0
c = c + b // 10 + 1 # 1의 자리
if a >= k:
c = c - a // 10
if a % 10 > k or k > b % 10:
c = c - 1
if b > 9 and b >= 10 * k: # 10의 자리
c = c + ((b // 100) * 10 + (b % 10)) + 1
if a >= 10 * k:
c = c - ((a // 100) * 10 + (a % 10)) + a % 10
if (a // 10) % 10 > k:
c = c - 10 + a % 10
if (b // 10) % 10 < k:
c = c - b % 10 - 1
if b > 99 and b >= 100 * k: # 100의 자리
c = c + ((b // 1000) * 100 + b % 100) + 1
if a >= 100 * k:
c = c - ((a // 1000) * 100 + a % 100) + a % 100
if (a // 100) % 10 > k:
c = c - 100 + a % 100
if (b // 100) % 10 < k:
c = c - b % 100 - 1
if b > 999 and b >= 1000 * k: # 1,000의 자리
c = c + ((b // 10000) * 1000 + b % 1000) + 1
if a >= 1000 * k:
c = c - ((a // 10000) * 1000 + a % 1000) + a % 1000
if (a // 1000) % 10 > k:
c = c - 1000 + a % 1000
if (b // 1000) % 10 < k:
c = c - b % 1000 - 1
if b > 9999 and b >= 10000 * k: # 10,000의 자리
c = c + ((b // 100000) * 10000 + b % 10000) + 1
if a >= 10000 * k:
c = c - ((a // 100000) * 10000 + a % 10000) + a % 10000
if (a // 10000) % 10 > k:
c = c - 10000 + a % 10000
if (b // 10000) % 10 < k:
c = c - b % 10000 - 1
if b > 99999 and b >= 100000 * k: # 100,000의 자리
c = c + ((b // 1000000) * 100000 + b % 100000) + 1
if a >= 100000 * k:
c = c - ((a // 1000000) * 100000 + a % 100000) + a % 100000
if (a // 100000) % 10 > k:
c = c - 100000 + a % 100000
if (b // 100000) % 10 < k:
c = c - b % 100000 - 1
if b > 999999 and b >= 1000000 * k: # 1,000,000의 자리
c = c + ((b // 10000000) * 1000000 + b % 1000000) + 1
if a >= 1000000 * k:
c = c - ((a // 10000000) * 1000000 + a % 1000000) + a % 1000000
if (a // 1000000) % 10 > k:
c = c - 1000000 + a % 1000000
if (b // 1000000) % 10 < k:
c = c - b % 1000000 - 1
print(c)