
#include <stdio.h>
#include <math.h>
int main(void)
{
	cal_distance(int x1,int x2,int y1,int y2)

		int X,Y;
		double D,d;

		X = x2 - x1;
		Y = y1 - y2;

		D = (X*X)(Y*Y);

		d = sprt(D);
		
		return (d);
}

int main(void)
{

	int  x1, x2, y1, y2;
	
	scanf("%d %d %d %d",x1, x2, y1, y2);
	
	distance = cal_distance(int x1,int x2,int y1,int y2);
	
	printf("%d"distance);

	return 0;

}