#include<cmath>

#include<cstdio>

#include<cstring>

#include<algorithm>

#define N 50003

#define read(x) x=getint()

#define sqr(x) (x)*(x)

using namespace std;

typedef long long LL;

inline int getint() {

	int k = 0, fh = 1; char c = getchar();

	for(; c < '0' || c > '9'; c = getchar())

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

	for(; c >= '0' && c <= '9'; c = getchar())

		k = k * 10 + c - '0';

	return k * fh;

}

struct node {

	int id, l, r;

} q[N];

LL sum, fz[N], fm[N], s[N];

int n, a[N], block[N], bel[N], m;

inline bool cmp(node A, node B) {return bel[A.l] == bel[B.l] ? A.r < B.r : A.l < B.l;}

inline void change(int x, int del) {

	sum -= sqr(s[x]);

	s[x] += del;

	sum += sqr(s[x]);

}

inline LL gcd(LL a, LL b) {

	return b ? gcd(b, a % b) : a;

}

int main() {

	read(n); read(m);

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

		read(a[i]);

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

		read(q[i].l), read(q[i].r), q[i].id = i;

	int t = ceil(sqrt(n)), tmp = 0, cnt = 0;

	for(int i = 1; i <= n; ++i) {

		bel[i] = cnt;

		++tmp;

		if (tmp == t)

			tmp = 0, ++cnt;

	}

	sort(q + 1, q + m + 1, cmp);

	int l = q[1].l, r = q[1].r;

	for(int i = l; i <= r; ++i) {

		sum -= sqr(s[a[i]]);

		++s[a[i]];

		sum += sqr(s[a[i]]);

	}

	fz[q[1].id] = sum - (r - l + 1);

	fm[q[1].id] = (r - l) * (r - l + 1);

	for(int i = 2; i <= m; ++i) {

		int tl = q[i].l, tr = q[i].r, tid = q[i].id;

		LL tlen = tr - tl + 1;

		while (l < tl) change(a[l++], -1);

		while (l > tl) change(a[--l], 1);

		while (r < tr) change(a[++r], 1);

		while (r > tr) change(a[r--], -1);

		fz[tid] = sum - tlen;

		fm[tid] = tlen * (tlen - 1);

	}

	for(int i = 1; i <= m; ++i) {

		if (fz[i] <= 0 || fm[i] <= 0)

			puts("0/1");

		else {

			LL tong = gcd(fz[i], fm[i]);

			printf("%lld/%lld\n", fz[i] / tong, fm[i] / tong);

		}

	}

	return 0;

}