import core.bitop, std.algorithm, std.ascii, std.bigint, std.conv, std.math,
    std.functional, std.numeric, std.range, std.stdio, std.string, std.random,
    std.typecons, std.container;

// dfmt off
T lread(T = long)(){return readln.chomp.to!T();}
T[] aryread(T = long)(){return readln.split.to!(T[])();}
void scan(TList...)(ref TList Args){auto line = readln.split();
foreach (i, T; TList){T val = line[i].to!(T);Args[i] = val;}}
alias sread = () => readln.chomp();enum MOD = 10 ^^ 9 + 7;
// dfmt on

void main()
{
    long N, M;
    scan(N, M);
    bool[long] A;
    foreach (i; 0 .. M)
        A[lread()] = true;
    auto dp = new long[](N + 2);
    dp[0] = 1;
    foreach (i; 0 .. N)
    {
        if (i + 1 !in A)
            dp[i + 1] = (dp[i + 1] + dp[i]) % MOD;
        if (i + 2 !in A)
            dp[i + 2] = (dp[i + 2] + dp[i]) % MOD;
    }
    // writeln(dp);
    writeln(dp[N]);
}
