#include <bits/stdc++.h>
using namespace std;
const double pi = acos(-1.0);
const int intmax = 0x3f3f3f3f;
double eps = 1e-6;
template <class T>
inline void checkmin(T &a, T b) {
  if (b < a) a = b;
}
template <class T>
inline void checkmax(T &a, T b) {
  if (b > a) a = b;
}
template <class T>
inline T sqr(T x) {
  return x * x;
}
template <class T>
inline T lowbit(T n) {
  return (n ^ (n - 1)) & n;
}
template <class T>
inline int countbit(T n) {
  return (n == 0) ? 0 : (1 + countbit(n & (n - 1)));
}
template <class T>
inline T checkmod(T n, T m) {
  return (n % m + m) % m;
}
inline int rand(int a, int b) {
  if (a >= b) return a;
  return rand() % (b - a) + a;
}
template <class T>
inline T gcd(T a, T b) {
  if (a < 0) return gcd(-a, b);
  if (b < 0) return gcd(a, -b);
  return (b == 0) ? a : gcd(b, a % b);
}
template <class T>
inline T lcm(T a, T b) {
  if (a < 0) return lcm(-a, b);
  if (b < 0) return lcm(a, -b);
  return a * (b / gcd(a, b));
}
template <class T>
inline T euclid(T a, T b, T &x, T &y) {
  if (a < 0) {
    T d = euclid(-a, b, x, y);
    x = -x;
    return d;
  }
  if (b < 0) {
    T d = euclid(a, -b, x, y);
    y = -y;
    return d;
  }
  if (b == 0) {
    x = 1;
    y = 0;
    return a;
  } else {
    T d = euclid(b, a % b, x, y);
    T t = x;
    x = y;
    y = t - (a / b) * y;
    return d;
  }
}
template <class T>
inline vector<pair<T, int> > factorize(T n) {
  vector<pair<T, int> > R;
  for (T i = 2; n > 1;) {
    if (n % i == 0) {
      int C = 0;
      for (; n % i == 0; C++, n /= i)
        ;
      R.push_back(make_pair(i, C));
    }
    i++;
    if (i > n / i) i = n;
  }
  if (n > 1) R.push_back(make_pair(n, 1));
  return R;
}
template <class T>
inline bool isPrimeNumber(T n) {
  if (n <= 1) return false;
  for (T i = 2; i * i <= n; i++)
    if (n % i == 0) return false;
  return true;
}
template <class T>
inline T eularFunction(T n) {
  vector<pair<T, int> > R = factorize(n);
  T r = n;
  for (int i = 0; i < R.size(); i++) r = r / R[i].first * (R[i].first - 1);
  return r;
}
template <class T>
inline int dblcmp(T a, const T b) {
  a -= b;
  return a > eps ? 1 : (a < -eps ? -1 : 0);
}
template <class T>
inline int sgn(T a) {
  return a > eps ? 1 : (a < -eps ? -1 : 0);
}
struct vec2 {
  double x, y;
  vec2(double x = 0.0, double y = 0.0) : x(x), y(y) {}
  vec2 operator+(const vec2 &b) const { return vec2(x + b.x, y + b.y); }
  vec2 operator-(const vec2 &b) const { return vec2(x - b.x, y - b.y); }
  vec2 operator*(const double &b) const { return vec2(x * b, y * b); }
  vec2 operator/(const double &b) const { return vec2(x / b, y / b); }
  double operator*(const vec2 &b) const { return x * b.x + y * b.y; }
  double operator^(const vec2 &b) const { return x * b.y - y * b.x; }
  double len() { return sqrt(x * x + y * y); }
  vec2 unit() { return *this / len(); }
  vec2 rotate(double r) {
    vec2 t(sin(r), cos(r));
    return vec2(*this ^ t, *this * t);
  }
  bool operator<(const vec2 &b) const {
    if (dblcmp(x, b.x) != 0)
      return dblcmp(x, b.x) < 0;
    else
      return dblcmp(y, b.y) < 0;
  }
};
int main() {
  long long k, b, n;
  long long temp;
  while (cin >> k >> b >> n) {
    long long ans = 0;
    map<long long, int> m;
    m[0]++;
    long long sum = 0;
    long long sub = 0, cnt0 = 0;
    for (int i = 0; i < n; ++i) {
      cin >> temp;
      if (temp == 0) {
        cnt0++;
      } else {
        sub += cnt0 * (cnt0 + 1) / 2;
        cnt0 = 0;
      }
      sum = (sum + temp) % (k - 1);
      temp = sum;
      if (m.find(checkmod(temp - b, k - 1)) != m.end()) {
        ans += m[checkmod(temp - b, k - 1)];
      }
      m[temp]++;
    }
    sub += cnt0 * (cnt0 + 1) / 2;
    if (b == k - 1) ans -= sub;
    if (b == 0) ans = sub;
    cout << ans << endl;
  }
  return 0;
}

### Prompt

Please create a solution in cpp to the following problem:

You know that the Martians use a number system with base k. Digit b (0 ≤ b < k) is considered lucky, as the first contact between the Martians and the Earthlings occurred in year b (by Martian chronology).

A digital root d(x) of number x is a number that consists of a single digit, resulting after cascading summing of all digits of number x. Word "cascading" means that if the first summing gives us a number that consists of several digits, then we sum up all digits again, and again, until we get a one digit number.

For example, d(35047) = d((3 + 5 + 0 + 4)7) = d(157) = d((1 + 5)7) = d(67) = 67. In this sample the calculations are performed in the 7-base notation.

If a number's digital root equals b, the Martians also call this number lucky.

You have string s, which consists of n digits in the k-base notation system. Your task is to find, how many distinct substrings of the given string are lucky numbers. Leading zeroes are permitted in the numbers.

Note that substring s[i... j] of the string s = a1a2... an (1 ≤ i ≤ j ≤ n) is the string aiai + 1... aj. Two substrings s[i1... j1] and s[i2... j2] of the string s are different if either i1 ≠ i2 or j1 ≠ j2.

Input

The first line contains three integers k, b and n (2 ≤ k ≤ 109, 0 ≤ b < k, 1 ≤ n ≤ 105).

The second line contains string s as a sequence of n integers, representing digits in the k-base notation: the i-th integer equals ai (0 ≤ ai < k) — the i-th digit of string s. The numbers in the lines are space-separated.

Output

Print a single integer — the number of substrings that are lucky numbers.

Please, do not use the %lld specifier to read or write 64-bit integers in С++. It is preferred to use the cin, cout streams or the %I64d specifier.

Examples

Input

10 5 6
3 2 0 5 6 1


Output

5

Input

7 6 4
3 5 0 4


Output

1

Input

257 0 3
0 0 256


Output

3

Note

In the first sample the following substrings have the sought digital root: s[1... 2] = "3 2", s[1... 3] = "3 2 0", s[3... 4] = "0 5", s[4... 4] = "5" and s[2... 6] = "2 0 5 6 1".

### Response

```cpp
#include <bits/stdc++.h>
using namespace std;
const double pi = acos(-1.0);
const int intmax = 0x3f3f3f3f;
double eps = 1e-6;
template <class T>
inline void checkmin(T &a, T b) {
  if (b < a) a = b;
}
template <class T>
inline void checkmax(T &a, T b) {
  if (b > a) a = b;
}
template <class T>
inline T sqr(T x) {
  return x * x;
}
template <class T>
inline T lowbit(T n) {
  return (n ^ (n - 1)) & n;
}
template <class T>
inline int countbit(T n) {
  return (n == 0) ? 0 : (1 + countbit(n & (n - 1)));
}
template <class T>
inline T checkmod(T n, T m) {
  return (n % m + m) % m;
}
inline int rand(int a, int b) {
  if (a >= b) return a;
  return rand() % (b - a) + a;
}
template <class T>
inline T gcd(T a, T b) {
  if (a < 0) return gcd(-a, b);
  if (b < 0) return gcd(a, -b);
  return (b == 0) ? a : gcd(b, a % b);
}
template <class T>
inline T lcm(T a, T b) {
  if (a < 0) return lcm(-a, b);
  if (b < 0) return lcm(a, -b);
  return a * (b / gcd(a, b));
}
template <class T>
inline T euclid(T a, T b, T &x, T &y) {
  if (a < 0) {
    T d = euclid(-a, b, x, y);
    x = -x;
    return d;
  }
  if (b < 0) {
    T d = euclid(a, -b, x, y);
    y = -y;
    return d;
  }
  if (b == 0) {
    x = 1;
    y = 0;
    return a;
  } else {
    T d = euclid(b, a % b, x, y);
    T t = x;
    x = y;
    y = t - (a / b) * y;
    return d;
  }
}
template <class T>
inline vector<pair<T, int> > factorize(T n) {
  vector<pair<T, int> > R;
  for (T i = 2; n > 1;) {
    if (n % i == 0) {
      int C = 0;
      for (; n % i == 0; C++, n /= i)
        ;
      R.push_back(make_pair(i, C));
    }
    i++;
    if (i > n / i) i = n;
  }
  if (n > 1) R.push_back(make_pair(n, 1));
  return R;
}
template <class T>
inline bool isPrimeNumber(T n) {
  if (n <= 1) return false;
  for (T i = 2; i * i <= n; i++)
    if (n % i == 0) return false;
  return true;
}
template <class T>
inline T eularFunction(T n) {
  vector<pair<T, int> > R = factorize(n);
  T r = n;
  for (int i = 0; i < R.size(); i++) r = r / R[i].first * (R[i].first - 1);
  return r;
}
template <class T>
inline int dblcmp(T a, const T b) {
  a -= b;
  return a > eps ? 1 : (a < -eps ? -1 : 0);
}
template <class T>
inline int sgn(T a) {
  return a > eps ? 1 : (a < -eps ? -1 : 0);
}
struct vec2 {
  double x, y;
  vec2(double x = 0.0, double y = 0.0) : x(x), y(y) {}
  vec2 operator+(const vec2 &b) const { return vec2(x + b.x, y + b.y); }
  vec2 operator-(const vec2 &b) const { return vec2(x - b.x, y - b.y); }
  vec2 operator*(const double &b) const { return vec2(x * b, y * b); }
  vec2 operator/(const double &b) const { return vec2(x / b, y / b); }
  double operator*(const vec2 &b) const { return x * b.x + y * b.y; }
  double operator^(const vec2 &b) const { return x * b.y - y * b.x; }
  double len() { return sqrt(x * x + y * y); }
  vec2 unit() { return *this / len(); }
  vec2 rotate(double r) {
    vec2 t(sin(r), cos(r));
    return vec2(*this ^ t, *this * t);
  }
  bool operator<(const vec2 &b) const {
    if (dblcmp(x, b.x) != 0)
      return dblcmp(x, b.x) < 0;
    else
      return dblcmp(y, b.y) < 0;
  }
};
int main() {
  long long k, b, n;
  long long temp;
  while (cin >> k >> b >> n) {
    long long ans = 0;
    map<long long, int> m;
    m[0]++;
    long long sum = 0;
    long long sub = 0, cnt0 = 0;
    for (int i = 0; i < n; ++i) {
      cin >> temp;
      if (temp == 0) {
        cnt0++;
      } else {
        sub += cnt0 * (cnt0 + 1) / 2;
        cnt0 = 0;
      }
      sum = (sum + temp) % (k - 1);
      temp = sum;
      if (m.find(checkmod(temp - b, k - 1)) != m.end()) {
        ans += m[checkmod(temp - b, k - 1)];
      }
      m[temp]++;
    }
    sub += cnt0 * (cnt0 + 1) / 2;
    if (b == k - 1) ans -= sub;
    if (b == 0) ans = sub;
    cout << ans << endl;
  }
  return 0;
}

```