#include<iostream>
#include<cmath>
using namespace std;
int main(){
	int n,a,b;
	double max=0;
	cin>>n;
	for(int i=0;i<n;i++){
		cin>>a>>b;
		double r=sqrt(a*a+b*b);
		if(r>max)max=r;
	}
	printf("%.2f",max);
    return 0;
}