[Dayrion]

Код:

new playersJoined; 

public OnPlayerConnect(playerid) { 

    if(++playersJoined >= 20)
    {
		new string[128];
		format(string, sizeof(string), "Now player reached at %d players", playersJoined);
		SendClientMessage(playerid, -1, string);
		//Your other code give player money and bla bla bla as you want.
    } 
    return true; 
} 

public OnPlayerDisconnect(playerid, reason) { 

    playersJoined --; 
    return true; 
}