#include <stdio.h>
#include <math.h>

struct point
{
    int xpos;
    int ypos;
};

int main() {
    struct point pos1, pos2;
    double distance;

    fputs("point1 pos: ", stdout);
    scanf("%d %d", &pos1.xpos, &pos1.ypos);
    
    fputs("point2 pos: ", stdout);
    scanf("%d %d", &pos2.xpos, &pos2.ypos);

    distance=sqrt((double)((pos1.xpos-pos2.xpos) * (pos1.xpos-pos2.xpos)+ (pos1.ypos-pos2.ypos) * (pos1.ypos-pos2.ypos)));

    printf("두 점의 거리는 %g 입니다. \n", distance);
    
    return 0;
}