#include <bits/stdc++.h>
using namespace std;
const int N=80+5;
const int M=100+5;
const int P=20+5;
typedef long long ll;
ll ans=0;
int n,m,p;
int l[M],s[M],cnt=0;
ll f[N][M][P]={0};
ll gcd(ll x,ll y){
    if (y==0)return x;
    return gcd(y,x%y);
}
void init(int pt,int lst,int num,int t){
    if (pt==m+1){
        s[++cnt]=t;
        l[cnt]=num;
        return ;
    }
    init(pt+1,0,num,(t<<1));
    if (lst==0)init(pt+1,1,num+1,(t<<1)+1);
    return ;
}
void solve(){
    f[0][1][0]=1;
    for (int i=1;i<=n;i++){
        for (int j=1;j<=cnt;j++){
            for (int k=l[j];k<=p;k++){
                for (int wxc=1;wxc<=cnt;wxc++){
                    if ((s[j]&s[wxc])==0&&l[j]+l[wxc]<=k){
                        f[i][j][k]+=f[i-1][wxc][k-l[j]];
                    }
                }
            }
        }
    }
    for (int i=1;i<=cnt;i++){
        ans+=f[n][i][p];
    }
}
int main(){
    freopen ("examtwo.in","r",stdin);
    freopen ("examtwo.out","w",stdout);
    scanf("%d%d%d",&n,&m,&p);
    if (m>n)swap(m,n);
    init(1,0,0,0);
    solve();
    ll tot=1;
    for (int i=1;i<=p;i++){
        tot*=n*m-i+1;
        tot/=i;
    }
    ll x=gcd(ans,tot);
    printf("%lld/%lld\n",tot/x,ans/x);
    return 0;
}