#include <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < (n); ++i)
using namespace std;
using ll = long long;
using P = pair<int,int>;

int main() {
    int n,m;
    cin >> n >> m;
    vector<int> broken(n+1);
    rep(i,m){
        int a;
        cin >> a;
        broken[a] = 1;
    }
    vector<int> dp(n+2);
    const int mod = 1000000007;
    dp[n] = 1;
    for(int i = n-1;i >= 0;i--){
        if(broken[i]){
            dp[i] = 0;
            continue;
        }
        dp[i] = (dp[i+1] + dp[i+2];) % mod
    }
    cout << dp[0] << endl;
}