dp

#include <iostream>
#include <vector>


int main() {
    int n, m;
    std::cin >> n >> m;
    std::vector<std::vector<char>> v(n, std::vector<char>(m));
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < m; ++j) {
            std::cin >> v[i][j];
        }
    }
    std::vector<std::vector<int>> v1(n, std::vector<int>(m, 0));
    std::vector<std::vector<int>> v2(n, std::vector<int>(m, 0));
    std::vector<std::vector<int>> v3(n, std::vector<int>(m, 0));
    std::vector<std::vector<int>> v4(n, std::vector<int>(m, 0));


    for (int i = 1; i < n; ++i) {
        for (int j = 1; j < m; ++j) {
            if (v[i - 1][j] == v[i][j] && v[i][j - 1] == v[i][j]) { //    |
                v1[i][j] = 1 + std::min(v1[i - 1][j], v1[i][j - 1]);//  ---
            }
        }
    }

    for (int i = 1; i < n; ++i) {
        for (int j = 0; j < m - 1; ++j) {
            if (v[i - 1][j] == v[i][j] && v[i][j + 1] == v[i][j]) { // |
                v2[i][j] = 1 + std::min(v2[i - 1][j], v2[i][j + 1]);// ---
            }
        }
    }

    for (int i = 0; i < n - 1; ++i) {
        for (int j = 0; j < m - 1; ++j) {
            if (v[i + 1][j] == v[i][j] && v[i][j + 1] == v[i][j]) { // ---
                v3[i][j] = 1 + std::min(v3[i + 1][j], v3[i][j + 1]);// |
            }
        }
    }

    for (int i = 0; i < n - 1; ++i) {
        for (int j = 1; j < m; ++j) {
            if (v[i + 1][j] == v[i][j] && v[i][j - 1] == v[i][j]) { // ---
                v4[i][j] = 1 + std::min(v4[i + 1][j], v4[i][j - 1]);//   |
            }
        }
    }
    int ans = n * m;
    for (int i = 1; i < n - 1; ++i) {
        for (int j = 1; j < m - 1; ++j) {
            ans += std::min(std::min(v1[i][j], v2[i][j]), std::min(v3[i][j], v4[i][j]));
        }
    }
    std::cout << ans << std::endl;
    return 0;
}