rank nation gold silver bronze total
rank
nation
gold
silver
bronze
total
number
number
number
number
number
number text number number number number
1 nigeria 14 12 9 35
how long is the list of countries that won any medals ?
WRB JJ VBD-AUX DT NN IN NNS WDT VBD DT NNS .
14
select count ( c2 ) from w where c6_number > 0