if(strcmp(command, "/up ", true) ==0)
	{
		new upnum;
		upnum = strval(strtok(cmdtext, index));

		SetPlayerPos(playerid, Float:x, Float:y, Float:z + upnum);

		return 1;
	}

Error:
C:\Program Files\Rockstar Games\GTA San Andreas\samp\alisfirst.pwn(229) : error 017: undefined symbol "x"

Line 229: 		SetPlayerPos(playerid, Float:x, Float:y, Float:z + upnum);