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

int main()
{
	int N, R, I, norm = 0;

	scanf("%d", &N);
	for (int i = 0; i < N; i++) {
		scanf("%d %d", &R, &I);
		if (R * R + I * I > norm)
			norm = R * R + I * I;
	}
	printf("%.2lf", sqrt(norm));

	return 0;
}