C :

#include<stdio.h>
int main()
{
    long long n;
    while(scanf("%lld",&n)!=EOF)
    {
        long long i=0;
        while(i<n)
        {
            n-=i;
            i++;
        }
        if(i%2==0)
            printf("%lld/%lld\n",n,i+1-n);
        else printf("%lld/%lld\n",i+1-n,n);
    }
    return 0;
}

C++ :

#include<cstdio>
#include<cstring>
#include<cmath>

using namespace std;

int main()
{
    long long n;
    while(~scanf("%lld", &n))
    {
        long long sum = 0;
        for(int i = 1; ; i++)
        {
            sum += i;
            if(sum >= n)
            {
                if(i & 1)
                {
                    printf("%lld/%lld\n", sum - n + 1, i - sum + n);
                }
                else
                {
                    printf("%lld/%lld\n", i - sum + n, sum - n + 1);
                }
                break;
            }
        }
    }
    return 0;
}