#include <regex>
#include <iostream>
#include <sstream>

int AsInt(const std::string& s)
{
    int r = 0;
    std::istringstream p(s);
    p >> r;
    return r;
}

void Parse(const std::string& s)
{
    std::regex r("^(\\s*[^\\s-]+) (\\d+)$");
    std::smatch m;

    if (!std::regex_match(s, m, r))
    {
        std::cout << "NO MATCH for string '" << s << "'" <<std::endl;
        return;
    }

    std::cout << "parsed string '" << s << "'" << std::endl;

    const std::string s1 = m[1].str();
    const int id = AsInt(m[2].str());
    std::cout << "s1 = '" << s1 << "', n = " << id << std::endl;
}

int main()
{
    const char* source[] = {"root 1", " root/folder 5", " root/folder/example1000 10", " a b c d 4", "a b c"};
    for(auto& i : source)
    {
        Parse(i);
    }
    return 0;
}