#include <stdio.h>

float rectArea(int width, int height) {
	return width*height;
}

float triArea(int base, int height) {
	return base*height/2.0;
}

typedef struct shape {
	int width;
	int height;
	float (*area)(int,int);
} shape;

float grabArea(shape *s) {
	return s->area(s->width,s->height);
}

int main(int argv, char *argc[]) {
	shape rectangle={30,40,&rectArea};
	shape triangle={30,40,&triArea};
	
	printf("%f\n%f\n",grabArea(&rectangle),grabArea(&triangle));
	
	return 0;
}