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

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 mode = 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;

    return 0;
}