#include <stdio.h>
#include <stdlib.h>
#include <math.h>
float getDistance(int x1, int y1, int x2, int y2) {
float res;
res
= sqrt((y2
- y1
) * (y2
- y1
) + (x2
- x1
) * (x2
- x1
)); return res;
};
int main() {
int x1, y1, x2, y2;
scanf("%d%d%d%d", &x1
, &y1
, &x2
, &y2
); printf("%0.2f", getDistance
(x1
, y1
, x2
, y2
)); return 0;
}
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