#include <iostream>
#include <regex>
int main()
{
std::string text = R"(11111111111111111111
11111111111111111111
11111111111111111111
11111111111110000000
11111111111000000000
11111111100011111100
11111111100111100000)";
std::regex re("^1+\n");
std::string str = std::regex_replace(text, re, "");
std::cout << str;
return 0;
}