Description：

Solution：

Code：

#include<algorithm>

#include<iostream>

#include<cstdlib>

#include<cstdio>

#include<cmath>

#include<cctype>

#include<cstring>

using namespace std;

inline int read()

{

	register int res = 0,f = 1;

	register char c = getchar();

	while(!isdigit(c))

	{

		if(c == '-')f = -1;

		c = getchar();

	}

	while(isdigit(c))

	{

		res = (res << 1) + (res << 3) + c - '0';

		c = getchar();

	}

	return res * f;

}

int n,L,R;

#define MAXN 100010

int a[MAXN << 1];

long long x,y;

double b[MAXN << 1];

int q[2][MAXN << 1],head[2],tail[2];

bool calc(double k)

{

	for(int i = 1;i <= 2 * n;++i)b[i] = a[i] - k;

	for(int i = 2;i <= 2 * n;++i)b[i] += b[i - 1];

	head[0] = head[1] = 1;tail[0] = tail[1] = 0;

	double ans = -100000000000;

	int len;

	for(int i = 1;i <= 2 * n;++i)

	{

		int c = (i & 1) ^ 1;

		if(q[c ^ 1][head[c ^ 1]] < i - R + 1)

		{

			++head[c ^ 1];

		}

		if(i - L + 1 >= 1)

		{

			int p = ((i - L + 1) & 1) ^ 1;

			while(head[p] <= tail[p] && b[q[p][tail[p]] - 1] >= b[i - L + 1 - 1])--tail[p];

			q[p][++tail[p]] = i - L + 1;

		}

		if(head[c ^ 1] <= tail[c ^ 1] && b[i] - b[q[c ^ 1][head[c ^ 1]] - 1] > ans)

		{

			ans = b[i] - b[q[c ^ 1][head[c ^ 1]] - 1];

			len = i - q[c ^ 1][head[c ^ 1]] + 1;

		}

	}

	if(ans >= 0)y = len;

	return ans >= 0;

}

typedef long long ll;

ll gcd(ll a,ll b){return (b == 0 ? a : gcd(b,a % b));}

int main()

{

	scanf("%d%d%d",&n,&L,&R);

	for(int i = 1;i <= n;++i)a[i] = read();

	for(int i = 1;i <= n;++i)a[i + n] = a[i];

	double l = 0,r = 1000000000,mid;

	for(int i = 1;i <= 60;++i)

	{

		mid = (l + r) / 2;

		if(calc(mid))l = mid;

		else r = mid;

	}

	x = y * l + 0.5;

	ll g = gcd(x,y);x /= g;y /= g;

	if(y == 1)cout << x << endl;

	else cout << x << "/" << y << endl;

	return 0;

}