>>670

#include <stdio.h>

int main ( void )
{
int i ;
int n, r ;
int tn=1,tr=1 ;

printf ( "n=" ) ; scanf ( "%d", &n ) ;
printf ( "r=" ) ; scanf ( "%d", &r ) ;

tn = n ; tr = r ;

for ( i = 1 ; i < r ; i++ ){
tn *= (n-i) ;
}
for ( i = r-1 ; i > 1 ; i-- ){
tr *= i ;
}

printf ( "%dC%d = %d通り\n", n, r, tn/tr ) ;
}