diff --git a/others/kirill`s/lab1/task18.cpp b/others/kirill`s/lab1/task18.cpp
index e1a3eeb..9b71547 100644
--- a/others/kirill`s/lab1/task18.cpp
+++ b/others/kirill`s/lab1/task18.cpp
@@ -2,6 +2,8 @@
 #include <fstream>
 #include <string>
 #include <sys/stat.h>
+#include <cstdlib>
+#include <cerrno>
 
 static bool file_exists(const std::string &path) {
     struct stat st{};
@@ -14,13 +16,30 @@ static std::string make_out_name(const std::string &in) {
     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 != 2) {
-        std::cerr << "Usage: " << argv[0] << " <input_file>\n";
+    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;
@@ -43,10 +62,10 @@ int main(int argc, char *argv[]) {
     std::string line;
 
     while (std::getline(in, line)) {
-        if (!line.empty()) {
-            for (std::size_t idx = 0; idx < line.size(); ++idx) {
+        if (!line.empty() && replacements < target) {
+            for (std::size_t idx = 0; idx < line.size() && replacements < target; ++idx) {
                 std::size_t pos1 = idx + 1;
-                if (pos1 % 3 == 0) {
+                if ((pos1 % 3) == 0) {
                     if (line[idx] != ' ') {
                         line[idx] = ' ';
                         ++replacements;
@@ -62,6 +81,16 @@ int main(int argc, char *argv[]) {
         }
     }
 
+    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 static_cast<int>(replacements);
+    return 0;
 }