#include<bits/stdc++.h>
using namespace std;

int main(void){

    int N,M;
    cin>>N>>M;

    vector<int> dp(N+1, true);
    int tmp;
    for (int i = 0; i < M; ++i) {
        cin>>tmp;
        dp[tmp] = false;
    }

    for (int i = 2; i <= N; ++i) {
        if(dp[i] == false) continue;
        dp[i] = dp[i-1]+dp[i-2];
        dp[i] %= 1000000007;
    }

    cout <<dp[N]<<endl;

    return 0;
}