#include <iostream>
#include <cmath>
#include <cstdio>
using namespace std;
#define f first
#define s second
#define mp make_pair
#define pb push_back
#define INF (1<<30)
#define ll long long
const int N = 25;
ll f(ll x, int k)
{
  if (x == 0) return 0;
  int c[N] = {0}, len = 0;
  ll ans = 0, dp[4][N][11][2] = {0};
  while (x)
  {
    c[++len] = x % 10;
    x /= 10;
  }
  for (int i = 1; i <= len / 2; i++) swap(c[i], c[len - i + 1]);

  for (int l = 1; l <= len; l++)
    for (int cf = 1; cf < 10; cf++)
    {
      int v = 1, p;
      while (v <= l && cf == c[v]) v++;
      if (v == l + 1) p = 1;
      else if (cf > c[v]) p = 2;
      else p = 0;
      dp[p][l][cf][l >= k] = 1;
    }
  for (int l = 1; l <= len; l++)
    for (int p = 0; p < 3; p++)
      for (int cf = 0; cf < 10; cf++)
        for (int g = 0; g < 2; g++)
          for (int nc = 0; nc < 10; nc++)
            if (nc != cf)
            {
              int top = p;
              for (int add = 1; add <= len - l; add++)
              {
                if (top == 1 && nc > c[l + add]) top = 2;
                else if (top == 1 && nc < c[l + add]) top = 0;
                dp[top][l + add][nc][g | (add >= k)] += dp[p][l][cf][g];
              }
            }
  for (int l = 1; l <= len; l++)
    for (int p = 0; p < (l == len ? 2: 3); p++)
      for (int cf = 0; cf < 10; cf++) ans += dp[p][l][cf][1];
  return ans;
}

int main()
{
  //freopen("interesting.in", "r", stdin);
  //freopen("interesting.out", "w", stdout);
  ll a, b;
  int k;
  cin >> a >> b >> k;
  cout << f(b, k) - f(a - 1, k);
  return 0;
}