#include #include #include #include #include #define REP(i, n) for(int (i) = 0; (i) < (n); ++(i)) #define eREP(i, n) for(int (i) = 0; (i) <= (n); ++(i)) #define ALL(TheArray) TheArray.begin(), TheArray.end() template inline T& chmax(T& a, T b){return (a < b) ? a = b : a;} template inline T& chmin(T& a, T b){return (a > b) ? a = b : a;} using lli = long long int; constexpr int ALPHABET = 'z' - 'a' + 1; std::vector S; std::vector> Count[ALPHABET]; int main(void){ int H, W, k; std::cin >> H >> W >> k; S.resize(H); REP(i, H) std::cin >> S[i]; REP(x, ALPHABET){ char c = 'a' + x; Count[x].resize(H + 1, std::vector(W + 1)); REP(i, H) REP(j, W) Count[x][i+1][j+1] = (S[i][j] == c) ? 1 : 0; REP(i, H+1) Count[x][i][0] = 0; REP(j, W+1) Count[x][0][j] = 0; REP(i, H+1) REP(j, W) Count[x][i][j+1] += Count[x][i][j]; REP(j, W+1) REP(i, H) Count[x][i+1][j] += Count[x][i][j]; } lli res = 0; REP(i, H){ REP(j, W){ int t = 1; while(i + t <= H and j + t <= W){ int cnt = 0; REP(x, ALPHABET){ if(Count[x][i+t][j+t] - Count[x][i+t][j] - Count[x][i][j+t] + Count[x][i][j] > 0) cnt++; if(cnt > k) break; } if(cnt == k) res++; t++; } } } std::cout << res << '\n'; return 0; }