in how many territories were the wars fought where mk 20 mod 0 grenade launcher were used ?
SELECT DISTINCT COUNT attr_open var_uri attr_close where brack_open dbr_Mk_20_Mod_0_grenade_launcher dbo_usedInWar var_x sep_dot var_x dbo_territory var_uri sep_dot var_x a dbo_MilitaryConflict brack_close