#include <iostream>
#include <fstream>
#include <string>
#include <sys/stat.h>
#include <cerrno>
#include <cstdlib>

static bool file_exists(const std::string &path) {
    struct stat st{};
    return ::stat(path.c_str(), &st) == 0;
}

static std::string make_out_name(const std::string &in) {
    std::size_t pos = in.find_last_of('.');
    if (pos == std::string::npos) return in + ".out";
    return in.substr(0, pos) + ".out";
}

static bool parse_nonneg_ll(const char *s, long long &out) {
    if (!s || *s == '\0') return false;
    char *end = nullptr;
    errno = 0;
    long long v = std::strtoll(s, &end, 10);
    if (errno != 0 || end == s || *end != '\0') return false;
    if (v < 0) return false;
    out = v;
    return true;
}

int main(int argc, char *argv[]) {
    if (argc != 3) {
        std::cerr << "Usage: " << argv[0] << " input_file replace_count\n";
        return -1;
    }

    std::string in_path = argv[1];
    long long target = 0;
    if (!parse_nonneg_ll(argv[2], target)) {
        std::cerr << "Usage: " << argv[0] << " input_file replace_count\n";
        return -1;
    }

    if (!file_exists(in_path)) {
        std::cerr << "Error: input file does not exist.\n";
        return -1;
    }

    std::ifstream in(in_path);
    if (!in) {
        std::cerr << "Error: cannot open input file.\n";
        return -1;
    }

    std::string out_path = make_out_name(in_path);
    std::ofstream out(out_path);
    if (!out) {
        std::cerr << "Error: cannot create output file.\n";
        return -1;
    }

    long long replacements = 0;
    std::string line;

    while (std::getline(in, line)) {
        if (!line.empty() && replacements < target) {
            for (std::size_t i = 1; i < line.size() && replacements < target; ++i) {
                if (line[i] == line[i - 1]) {
                    if (line[i] != ' ') {
                        line[i] = ' ';
                        ++replacements;
                    }
                }
            }
        }
        out << line;
        if (!in.eof()) out << '\n';
        if (!out) {
            std::cerr << "Error: write error.\n";
            return -1;
        }
    }

    if (!in.eof() && in.fail()) {
        std::cerr << "Error: read error.\n";
        return -1;
    }

    if (replacements != target) {
        std::cerr << "Error: could not perform exactly requested replacements.\n";
        return -1;
    }

    std::cout << replacements << std::endl;
    return 0;
}