#include<stdio.h>
double seki(double x, double y);
int main(void)
{
 double (*p)(double x, double y) ;
 double n1 = 2.0;
 double n2 = 3.0;
 p=seki;
 printf("%lf¥n", (*p)(n1,n2));
 return 0;
}
double seki(double x, double y)
{
 return x * y;
}