#include <bits/stdc++.h>
using namespace std;
void __print(int x) { cerr << x; }
void __print(long x) { cerr << x; }
void __print(long long x) { cerr << x; }
void __print(unsigned x) { cerr << x; }
void __print(unsigned long x) { cerr << x; }
void __print(unsigned long long x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\'' << x << '\''; }
void __print(const char *x) { cerr << '\"' << x << '\"'; }
void __print(const string &x) { cerr << '\"' << x << '\"'; }
void __print(bool x) { cerr << (x ? "true" : "false"); }
template <typename T, typename V>
void __print(const pair<T, V> &x) {
  cerr << '{';
  __print(x.first);
  cerr << ',';
  __print(x.second);
  cerr << '}';
}
template <typename T>
void __print(const T &x) {
  int f = 0;
  cerr << '{';
  for (auto &i : x) cerr << (f++ ? "," : ""), __print(i);
  cerr << "}";
}
void _print() { cerr << "]\n"; }
template <typename T, typename... V>
void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v)) cerr << ", ";
  _print(v...);
}
long long N, M;
long long steps[100001];
long long MOD = 1000000007;
priority_queue<long long, vector<long long>, greater<long long>> a;
void dp(long long current) {
  long long next;
  if (!a.empty()) {
    next = a.top();
  } else {
    next = -1;
  }
  if (current == next) {
    steps[current] = 0;
    a.pop();
  } else {
    steps[current] = (steps[current - 1] + steps[current - 2]) % MOD;
  }
  if (current == N) return;
  dp(current + 1);
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cin >> N >> M;
  for (int i = 0; i < (int)(M); i++) {
    long long tmp;
    cin >> tmp;
    a.push(tmp);
  }
  steps[0] = 1;
  if (a.top() == 1) {
    a.pop();
    steps[1] = 0;
  } else {
    steps[1] = 1;
  }
  dp(2);
  cout << steps[N] % MOD << endl;
  return 0;
}
