#include <bits/stdc++.h>
using namespace std;
const long double PI = 3.1415926535897932384626;
const long long int MOD = 1000000000 + 7;
const int INF = 0x3f3f3f3f;
template <typename Arg1>
void __f(const char *name, Arg1 &&arg1) {
  cerr << name << " : " << arg1 << std::endl;
}
template <typename Arg1, typename... Args>
void __f(const char *names, Arg1 &&arg1, Args &&...args) {
  const char *comma = strchr(names + 1, ',');
  cerr.write(names, comma - names) << " : " << arg1 << " | ";
  __f(comma + 1, args...);
}
long long int Nmul(long long int A, long long int B) {
  long long int ret = (long long int)((long long int)(A) * (long long int)(B));
  return ret;
}
long long int Mmul(long long int a, long long int b, long long int mod) {
  long long int c = Nmul(a, b);
  c %= mod;
  while (c < 0) {
    c += mod;
  };
  return c;
}
long long int Nadd(long long int A, long long int B) {
  long long int ret = (long long int)((long long int)(A) + (long long int)(B));
  return ret;
}
long long int Madd(long long int a, long long int b, long long int mod) {
  long long int c = Nadd(a, b);
  while (c >= mod) {
    c -= mod;
  };
  while (c < 0) {
    c += mod;
  };
  return c;
}
long long int Nsub(long long int A, long long int B) {
  long long int ret = (long long int)((long long int)(A) - (long long int)(B));
  return ret;
}
long long int Msub(long long int a, long long int b, long long int mod) {
  return Madd(a, mod - b, mod);
}
long long int Npow(long long int A, long long int p) {
  long long int ret = 1;
  while (p) {
    if (p & 1) {
      ret = (ret * A);
    }
    A = (A * A);
    p >>= 1;
  }
  return ret;
}
long long int Mpow(long long int a, long long int n, long long int b) {
  long long int res = 1;
  while (n) {
    if (n & 1) {
      res = Mmul(res, a, b);
    }
    a = Mmul(a, a, b);
    n >>= 1;
  }
  return Madd(res, 0, b);
}
long long int Ndiv(double A, double B, bool ud) {
  if (B) {
    double ret = (double)(A) / (double)(B);
    if (ud) return ceil(ret);
    return floor(ret);
  }
  return INF;
}
long long int Mdiv(long long int a, long long int b, long long int mod) {
  long long int ans = Mmul(a, Mpow(b, mod - 2, mod), mod);
  return ans;
}
int pre[1600 + 1];
int ans = 0;
int k;
string a, b;
struct trie {
  trie *child[27];
  bool is_word;
  trie *new_node() {
    trie *tmp = new trie;
    for (int i = 0; i < 26; i++) tmp->child[i] = NULL;
    tmp->is_word = 0;
    return tmp;
  }
  void addword(trie *root, int idx, int p) {
    trie *tmp = root;
    int ch, lmt;
    for (int i = idx; i < p; i++) {
      ch = (int)(a[i] - 'a');
      if (idx)
        lmt = pre[i] - pre[idx - 1];
      else
        lmt = pre[i];
      if (lmt <= k) {
        if (tmp->child[ch] == NULL) {
          ans++;
          tmp->child[ch] = new_node();
        }
        tmp = tmp->child[ch];
      } else
        return;
    }
  }
};
int main(int argc, char const *argv[]) {
  trie *root;
  root = root->new_node();
  cin >> a >> b >> k;
  for (int i = 0; i < a.size(); i++) {
    if (i) {
      pre[i] = pre[i - 1];
      if ((int)('1' - b[a[i] - 'a'])) pre[i] += 1;
    } else {
      if ((int)('1' - b[a[i] - 'a']))
        pre[i] = 1;
      else
        pre[i] = 0;
    }
  }
  int p = a.size();
  for (int i = 0; i < p; i++) {
    root->addword(root, i, p);
  }
  cout << ans << endl;
  return 0;
}
