#!/usr/bin/awk

BEGIN {
	integral = 0;
	prev_x   = 0;
	prev_y   = 0;
}

{
	cur_x = $1;
	cur_y = $2;

	if (NR != 1) {
		integral += (cur_x - prev_x)*(cur_y + prev_y)/2;
	}
	prev_x = cur_x;
	prev_y = cur_y;
	
	printf "%6g\t%6g\n", cur_x, integral;

}