#include #define ADD(a, b) a = (a + ll(b)) % mod #define MUL(a, b) a = (a * ll(b)) % mod #define MAX(a, b) a = max(a, b) #define MIN(a, b) a = min(a, b) #define rep(i, a, b) for(int i = int(a); i < int(b); i++) #define rer(i, a, b) for(int i = int(a) - 1; i >= int(b); i--) #define all(a) (a).begin(), (a).end() #define sz(v) (int)(v).size() #define pb push_back #define sec second #define fst first #define debug(fmt, ...) Debug(__LINE__, ":", fmt, ##__VA_ARGS__) using namespace std; typedef long long ll; typedef unsigned long long ull; typedef pair pi; typedef pair pl; typedef pair ppi; typedef vector vi; typedef vector vl; typedef vector mat; typedef complex comp; void Debug() {cerr << '\n'; } templatevoid Debug(FIRST arg, REST... rest){ cerr<ostream& operator<<(ostream& out,const vector& v) { out<<"[";if(!v.empty()){rep(i,0,sz(v)-1)out<ostream& operator<<(ostream& out,const pair& v){ out<<"("< B; void init(int n, int m) { N = n; M = m; B = vector(N + 1, vi(M + 1, 0)); } Ruiseki2D() {} Ruiseki2D(int n, int m) { init(n, m); } void add(int a, int b, int v) { if(a < 0 || N <= a || b < 0 || M <= b) return; B[a + 1][b + 1] += v; } void sweep() { rep(i, 1, N + 1) rep(j, 1, M + 1) B[i][j] += B[i][j - 1] + B[i - 1][j] - B[i - 1][j - 1]; } ll get(int a, int b, int c, int d) { //[(a, b), (c, d)) if(a >= c || b >= d) return 0; a = max(a, 0); b = max(b, 0); c = min(c, N); d = min(d, M); return B[c][d] - B[c][b] - B[a][d] + B[a][b]; } }; int N, M, K; Ruiseki2D R[26]; void solve() { cin >> N >> M >> K; rep(i, 0, 26) R[i].init(N, M); rep(i, 0, N) { rep(j, 0, M) { char a; cin >> a; R[a - 'a'].add(i, j, 1); // debug(i, j, a); } } rep(i, 0, 26) R[i].sweep(); auto get = [&](int i, int j, int L) { int lv = 0, rv = min(N - i, M - j) + 1; while(rv - lv > 1) { int m = (lv + rv) / 2; int tmp = 0; rep(k, 0, 26) { if(R[k].get(i, j, i + m, j + m)) tmp++; } if(tmp >= L) rv = m; else lv = m; } return rv; }; ll res = 0; rep(i, 0, N) { rep(j, 0, M) { res += get(i, j, K + 1) - get(i, j, K); // debug(get(i, j, K + 1), get(i, j, K)); } } cout << res << "\n"; } uint32_t rd() { uint32_t res; #ifdef __MINGW32__ asm volatile("rdrand %0" :"=a"(res) ::"cc"); #else res = std::random_device()(); #endif return res; } int main() { #ifndef LOCAL ios::sync_with_stdio(false); cin.tie(0); #endif cout << fixed; cout.precision(20); cerr << fixed; cerr.precision(6); rng.seed(rd()); #ifdef LOCAL //freopen("in.txt", "wt", stdout); //for tester if(!freopen("in.txt", "rt", stdin)) return 1; #endif solve(); cerr << "Time: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n"; return 0; }