#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 5e2 + 1;
int n, m, k;
char grid[N][N];
const int dr[] = {1, 1, 1, 0, 0, -1, -1, -1};
const int dc[] = {1, -1, 0, 1, -1, 1, -1, 0};
string get_path(int r, int c, int d) {
string res;
for (int step = 0; step < k; step++) {
res += grid[r][c];
r = (r + dr[d] + n) % n;
c = (c + dc[d] + m) % m;
}
return res;
}
struct Hash {
const int M = 1e9 + 9;
const int P = 9973;
int n;
vector<ll> pw, hsh;
ll mul(ll a, ll b) { return (a * b) % M; }
ll add(ll a, ll b) { return (a + b) % M; }
ll sub(ll a, ll b) { return (a - b + M) % M; }
Hash(string s) {
n = s.size();
pw.resize(k + 1); // Precompute up to k
hsh.resize(n + 1);
pw[0] = 1;
hsh[0] = 0;
for (int i = 1; i <= n; i++) {
pw[i] = mul(pw[i - 1], P);
hsh[i] = add(s[i - 1], mul(hsh[i - 1], P));
}
for (int i = n + 1; i <= k; i++) {
pw[i] = mul(pw[i - 1], P);
}
}
ll get(int l, int r) {
return sub(hsh[r + 1], mul(hsh[l], pw[r - l + 1]));
}
ll merge(ll lval, ll rval, int rsize) {
return add(rval, mul(lval, pw[rsize]));
}
ll getByStart(int i) {
return merge(get(i, n - 1), get(0, i - 1), n - i);
}
};
void solve() {
cin >> n >> m >> k;
for (int i = 0; i < n; i++)
for (int j = 0; j < m; j++)
cin >> grid[i][j];
map<ll, ll> mp;
for (int r = 0; r < n; r++) {
for (int c = 0; c < m; c++) {
for (int d = 0; d < 8; d++) {
string s = get_path(r, c, d);
Hash hsh(s);
ll full_hash = hsh.get(0, k - 1);
mp[full_hash]++;
}
}
}
ll den = (1ll * n * m * 8) * (1ll * n * m * 8);
ll num = 0;
for (auto& [hash, cnt] : mp) {
num += 1ll * cnt * cnt;
}
if (num == 0) {
cout << "0/1" << endl;
} else {
ll GCD = gcd(num, den);
cout << num / GCD << "/" << den / GCD << endl;
}
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int t = 1;
while (t--) solve();
return 0;
}
