#include <bits/stdc++.h>
int main() {
  long ans;
  int i, j, n[101], k, nn;
  char s[101];
  scanf("%s", s);
  scanf("%d", &k);
  for (i = 0; s[i] != '\0'; i++) n[i] = s[i] - '0';
  nn = i;
  if (nn < k)
    puts("0");
  else if (k == 1) {
    printf("%d\n", n[0] + (nn - 1) * 9);
  } else if (k == 2) {
    ans = n[1];
    ans += 9 * (nn - 2);
    ans += (n[0] - 1) * 9 * (nn - 1);
    for (i = 1; i < nn - 1; i++) ans += 9 * 9 * i;
    printf("%ld\n", ans);
  } else {
    ans = n[1] * n[2];
    ans += n[1] * 9 * (nn - 3);
    ans += 9 * 9 * (nn - 2) * (nn - 3) / 2;
    ans += (n[0] - 1) * 9 * 9 * (nn - 1) * (nn - 2) / 2;
    ans += 9 * 9 * 9 * (nn - 1) * (nn - 2) * (nn - 3) / 6;
    printf("%ld\n", ans);
  }
  return 0;
}
