#include
#include
int main()
{
int n;
double max=-1;
scanf("%d",&n);
while(n--)
{
double a,b,ans;
scanf("%lf %lf",&a,&b);
ans=sqrt(a*a+b*b);
if(ans>max)max=ans;
}
printf("%.2lf",max);
return 0;
}