#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<stack>
using namespace std;
int main()
{
	long long int k,n,m;
	cin>>k>>n>>m;
	if(k == 0 && n==0 && m==0)
	{
		cout<<1;
		return 0;
	}
	if(k == 0)
	{
		if((n+1)*(m+1) == 1)
			cout<<1;
		else
			cout<<1<<"/"<<(n+1)*(m+1)-1;
		return 0;
	}
	int positive = 0;
	int negative = 0;
	for(int i = 0;i<=n;i++)
	{
		for(int j = 0;j<=m;j++)
		{
			if((k - (i*2+j*3)) == 0)
				positive++;
			else
				negative++;
		}
	}
	if(positive % (positive+negative) == 0)
		cout<<positive/(positive+negative);
	else
		cout<<positive<<"/"<<positive+negative;
}