#include <bits/stdc++.h>

using namespace std;

string exec(const char* cmd) {
    char buffer[1024];
    std::string result;
    FILE* pipe = popen(cmd, "r");
    if (!pipe) return "Error";
    while (fgets(buffer, sizeof(buffer), pipe) != nullptr) {
        result += buffer;
    }
    pclose(pipe);
    return result;
}

signed main() {
#ifdef _WIN32
	string s = exec("dir");
	assert(!s.empty());
#else
	string s1 = exec("ls"), s2 = exec("ls ../");
	assert(s1 != s2);
#endif
}

/*
/
	unknown/
		?.cpp
		trans.in

*/