#include <bits/stdc++.h>
using namespace std;

namespace IO {
	#if ONLINE_JUDGE
	#define getc() (IS == IT && (IT = (IS = ibuf) + fread(ibuf, 1, IL, stdin), IS == IT) ? EOF : *IS++)
	#else
	#define getc() getchar()
	#endif
	const int IL = 1 << 21, OL = 1 << 21;
	int olen = 0;
	char ibuf[IL], *IS = ibuf, *IT = ibuf, obuf[OL];
	inline int read() {
		register char ch = getc(); register int x = 0, f = 1;
		while(!isdigit(ch)) { if(ch == '-') f = -1; ch = getc(); }
		while(isdigit(ch)) x = x * 10 + ch - 48, ch = getc();
		return x * f;
	}
	inline double readdb() {
		register char ch = getc(); register double x = 0, f = 1;
		while(!isdigit(ch)) { if(ch == '-') f = -1; ch = getc(); }
		while(isdigit(ch)) x = x * 10 + ch - 48, ch = getc();
		if(ch == '.') {
			register double b = 0.1;
			ch = getc();
			while(isdigit(ch)) x += (ch - 48) * b, b *= 0.1, ch = getc();
		}
		return x * f;
	}
	inline int readstr(char *s) {
		register char ch = getc(); register int len = 0;
		while(!isalpha(ch)) ch = getc();
		while(isalpha(ch)) s[++len] = ch, ch = getc();
		return len;
	}
	inline void flush() { fwrite(obuf, 1, olen, stdout); olen = 0; }
	inline void putc(register char ch) { obuf[olen++] = ch; }
	template<class T>
	inline void write(register T x) {
		if(x < 0) obuf[olen++] = '-', x = -x;
		if(x > 9) write(x / 10);
		obuf[olen++] = x % 10 + 48;
	}
} using namespace IO;
const int N = 5e5 + 10;
int n;
struct vec {
	double x, y;
	vec(double X = 0, double Y = 0) { x = X, y = Y; }
	friend vec operator + (const vec &a, const vec &b)
		{ return vec(a.x + b.x, a.y + b.y); }
	friend vec operator - (const vec &a, const vec &b)
		{ return vec(a.x - b.x, a.y - b.y); }
} p[N], st[N];
int top;
double cross(vec a, vec b) { return a.x * b.y - a.y * b.x; }
double dis(vec a, vec b) { return sqrt((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y)); }
bool cmp(vec a, vec b) { return a.x == b.x ? a.y < b.y : a.x < b.x; }
int main() {
	n = read();
	for(int i = 1; i <= n; i++)
		p[i].x = read(), p[i].y = read();
	double ans = 0;
	for(int i = 1, cur = i; i <= n; i++) {
		while(dis(p[i], p[cur % n + 1]) >= dis(p[i], p[cur])) cur = cur % n + 1;
		ans = max(ans, dis(p[i], p[cur]));
	}
	printf("%.10lf", ans);
	return 0;
}