public boolean checkPassword(String pass){
		boolean band = true;
		int i=0;
		for(int x=0;x<4;x++){
			if(pass.charAt(x)<48 || pass.charAt(x)>57)
				return false;
		}
		while(band == true && i <= numClientes){
			if(pass.equals(clientes[i].getPassword()))
			  band = false;
			else
			  i++;
		}
		return band;	
	}