#include <bits/stdc++.h>
using namespace std;
long long fib(long long n) {
  if (n == 0 || n == 1) {
    return 1;
  } else {
    return fib(n - 1) + fib(n - 2);
  }
}
int main() {
  int N, M;
  long long c = 0;
  int pre = 1;
  cin >> N >> M;
  int a, b;
  for (int i = (0), iformax = (M); i < iformax; i++) {
    cin >> a;
    if (a == pre) {
      c = 0;
      break;
    } else {
      b = a - pre;
      c += fib(b);
      pre = a + 1;
    }
  }
  if (c == 0) {
    cout << 0 << endl;
  } else {
    b = N - pre;
    c += fib(b);
    cout << c % 1000000007 << endl;
  }
}
