#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
#define pb push_back
#define X first
#define Y second
#define sz(v) (int)v.size()

void solve();

main() {
	ios_base::sync_with_stdio(0), cin.tie(0);
#ifdef ONPC
	freopen("in.txt", "r", stdin);
#endif
	int t = 1;
	//cin >> t;
	while (t--) solve();
	return 0;
}

ll gcd(ll a, ll b, ll &x, ll &y) {
	if (a == 0) {
		x = 0;
		y = 1;
		return b;
	}
	ll xx, yy;
	ll g = gcd(b % a, a, xx, yy);
	x = yy - (b / a) * xx;
	y = xx;
	return g;
}

bool find_any(ll a, ll b, ll c, ll &x, ll &y, ll &g) {
	g = gcd(a, b, x, y);
	if (c % g != 0) return false;
	x *= c / g;
	y *= c / g;
	return true;
}

void shift(ll &x, ll &y, ll a, ll b, ll cnt) {
	x += cnt * b;
	y -= cnt * a;
}

ll find_all(ll a, ll b, ll c, ll minx, ll maxx, ll miny, ll maxy) {
	ll x, y, g;
	if (!find_any(a, b, c, x, y, g)) return 0;
	a /= g;
	b /= g;
	shift(x, y, a, b, (minx - x) / b);
	if (x < minx) shift(x, y, a, b, 1);
	if (x > maxx) return 0;
	ll lx1 = x;
	shift(x, y, a, b, (maxx - x) / b);
	if (x > maxx) shift(x, y, a, b, -1);
	ll rx1 = x;
	shift(x, y, a, b, -(miny - y) / a);
	if (y < miny) shift(x, y, a, b, -1);
	if (y > maxy) return 0;
	ll lx2 = x;
	shift(x, y, a, b, -(maxy - y) / a);
	if (y > maxy) shift(x, y, a, b, 1);
	ll rx2 = x;
	if (lx2 > rx2) swap(lx2, rx2);
	ll lx = max(lx1, lx2);
	ll rx = min(rx1, rx2);
	return (rx - lx) / b + 1;
}


ll n, a, b;

void solve() {
	long long nn, aa, bb;
	cin >> nn >> aa >> bb;
	n = nn;
	a = aa;
	b = bb;
	ll all = (a + 1) * (b + 1);
	ll cur = find_all(2, 3, n, 0, a, 0, b);
	ll g = __gcd(all, cur);
	if (cur == 0) {
		cout << 0;
		return;
	}
	if (cur == all) {
		cout << 1;
		return;
	}
	all /= g;
	cur /= g;
	string s = "";
	while (cur) {
		s += char(cur % 10 + '0');
		cur /= 10;
	}
	reverse(s.begin(), s.end());
	cout << s << '/';
	s = "";
	while (all) {
		s += char('0' + all % 10);
		all /= 10;
	}
	reverse(s.begin(), s.end());
	cout << s;
}