import std.stdio, std.conv, std.string, std.array, std.range, std.algorithm, std.container;
import std.math, std.random, std.bigint, std.datetime, std.format;
void main(string[] args){ if(args.length > 1) if(args[1] == "-debug") DEBUG = 1; solve(); }
void log()(){ writeln(""); } void log(T, A ...)(T t, lazy A a){ if(DEBUG) write(t, " "), log(a); } bool DEBUG = 0; 
string read(){ static string[] ss; while(!ss.length) ss = readln.chomp.split; string res = ss[0]; ss.popFront; return res; }
// ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- //

const long mod = 1_000_000_007;

void solve(){
	
	int n = read.to!int;
	int m = read.to!int;
	
	bool[] isBroken = new bool[](n + 1);
	foreach(i; 0 .. m){
		int a = read.to!int;
		isBroken[a] = 1;
	}
	
	int[] xs;
	foreach(i; 0 .. n + 1){
		if(i == 0) xs ~= 1;
		else if(i == 1) xs ~= (isBroken[1]? 0: 1);
		else{
			if(isBroken[i]) xs ~= 0;
			else xs ~= (xs[i -2] + xs[i - 1]) % mod;
		}
	}
	
	log("xs:", xs);
	xs[n].writeln;
	
}
