#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
template <class T>
using V = vector<T>;
template <class T>
using VV = V<V<T>>;
constexpr ll TEN(int n) { return (n == 0) ? 1 : 10 * TEN(n - 1); }
template <class T, class U>
void chmin(T& t, const U& u) {
  if (t > u) t = u;
}
template <class T, class U>
void chmax(T& t, const U& u) {
  if (t < u) t = u;
}
template <class T, class U>
ostream& operator<<(ostream& os, const pair<T, U>& p) {
  os << "(" << p.first << "," << p.second << ")";
  return os;
}
template <class T>
ostream& operator<<(ostream& os, const vector<T>& v) {
  os << "{";
  for (int i = 0; i < (v.size()); i++) {
    if (i) os << ",";
    os << v[i];
  }
  os << "}";
  return os;
}
template <unsigned int MOD>
struct ModInt {
  using uint = unsigned int;
  using ull = unsigned long long;
  using M = ModInt;
  uint v;
  ModInt(ll _v = 0) { set_norm(_v % MOD + MOD); }
  M& set_norm(uint _v) {
    v = (_v < MOD) ? _v : _v - MOD;
    return *this;
  }
  explicit operator bool() const { return v != 0; }
  M operator+(const M& a) const { return M().set_norm(v + a.v); }
  M operator-(const M& a) const { return M().set_norm(v + MOD - a.v); }
  M operator*(const M& a) const { return M().set_norm(ull(v) * a.v % MOD); }
  M operator/(const M& a) const { return *this * a.inv(); }
  M& operator+=(const M& a) { return *this = *this + a; }
  M& operator-=(const M& a) { return *this = *this - a; }
  M& operator*=(const M& a) { return *this = *this * a; }
  M& operator/=(const M& a) { return *this = *this / a; }
  M operator-() const { return M() - *this; }
  M& operator++(int) { return *this = *this + 1; }
  M& operator--(int) { return *this = *this - 1; }
  M pow(ll n) const {
    if (n < 0) return inv().pow(-n);
    M x = *this, res = 1;
    while (n) {
      if (n & 1) res *= x;
      x *= x;
      n >>= 1;
    }
    return res;
  }
  M inv() const {
    ll a = v, b = MOD, p = 1, q = 0, t;
    while (b != 0) {
      t = a / b;
      swap(a -= t * b, b);
      swap(p -= t * q, q);
    }
    return M(p);
  }
  bool operator==(const M& a) const { return v == a.v; }
  bool operator!=(const M& a) const { return v != a.v; }
  friend ostream& operator<<(ostream& os, const M& a) { return os << a.v; }
  static int get_mod() { return MOD; }
};
using Mint = ModInt<1000000007>;
const Mint zero(0);
const Mint one(1);
bool iszero(Mint x) { return x.v == 0; }
bool isone(Mint x) { return x.v == 1; }
template <class T>
struct Matrix {
  int H, W;
  VV<T> a;
  Matrix() : H(0), W(0) {}
  Matrix(int H, int W) : H(H), W(W), a(VV<T>(H, V<T>(W))) {}
  Matrix(const VV<T>& v) : H(v.size()), W(v[0].size()), a(v) {}
  static Matrix E(int n) {
    Matrix a(n, n);
    for (int i = 0; i < (n); i++) a.set(i, i, 1);
    return a;
  }
  T at(int i, int j) const { return a[i][j]; }
  void set(int i, int j, T v) { a[i][j] = v; }
  Matrix operator+(const Matrix& r) const {
    assert(H == r.H && W == r.W);
    VV<T> v(H, V<T>(W));
    for (int i = 0; i < (H); i++)
      for (int j = 0; j < (W); j++) v[i][j] = a[i][j] + r.a[i][j];
    return Matrix(v);
  }
  Matrix operator-(const Matrix& r) const {
    assert(H == r.H && W == r.W);
    VV<T> v(H, V<T>(W));
    for (int i = 0; i < (H); i++)
      for (int j = 0; j < (W); j++) v[i][j] = a[i][j] - r.a[i][j];
    return Matrix(v);
  }
  Matrix operator*(const Matrix& r) const {
    assert(W == r.H);
    VV<T> v(H, V<T>(r.W));
    for (int i = 0; i < (H); i++)
      for (int k = 0; k < (W); k++)
        for (int j = 0; j < (r.W); j++) v[i][j] += a[i][k] * r.a[k][j];
    return Matrix(v);
  }
  Matrix& operator+=(const Matrix& r) { return (*this) = (*this) + r; }
  Matrix& operator-=(const Matrix& r) { return (*this) = (*this) - r; }
  Matrix& operator*=(const Matrix& r) { return (*this) = (*this) * r; }
  Matrix pow(ll n) const {
    assert(H == W);
    int h = H;
    Matrix x = *this, res(h, h);
    res = E(h);
    while (n > 0) {
      if (n & 1) res *= x;
      x *= x;
      n >>= 1;
    }
    return res;
  }
  friend ostream& operator<<(ostream& o, const Matrix& A) {
    for (int i = 0; i < (A.H); i++) {
      for (int j = 0; j < (A.W); j++) o << A.a[i][j] << " ";
      o << endl;
    }
    return o;
  }
};
vector<int> pre_kmp(string pat) {
  int k;
  vector<int> table((int)pat.size() + 1);
  table[0] = -1;
  for (int i = 1; i <= pat.size(); ++i) {
    k = table[i - 1];
    while (k >= 0) {
      if (pat[k] == pat[i - 1])
        break;
      else
        k = table[k];
    }
    table[i] = k + 1;
  }
  return table;
}
using Mat = Matrix<Mint>;
int nxt[110][2];
V<int> pf;
string s;
int n;
Mat proc(int c) {
  Mat A(n + 2, n + 2);
  int ap = n + 1;
  A.set(ap, ap, 2);
  for (int i = 0; i <= n; ++i) {
    A.a[i][i]++;
    int nx = i;
    if (i == n) {
      nx = pf[nx];
    }
    while (nx >= 0 && s[nx] != '0' + c) {
      nx = pf[nx];
    }
    nx++;
    if (nx == n) {
      A.a[i][ap]++;
      nx = pf[nx];
    }
    A.a[i][nx]++;
  }
  return A;
}
int main() {
  int x;
  cin >> n >> x;
  cin >> s;
  pf = pre_kmp(s);
  (void(0));
  Mat a = proc(0), b = proc(1);
  for (int i = 2; i <= x; ++i) {
    auto c = b * a;
    a = b;
    b = c;
  }
  if (x == 0) {
    b = a;
  }
  Mat res(1, n + 2);
  res.set(0, 0, 1);
  res = res * b;
  cout << res.at(0, n + 1) << endl;
  return 0;
}
