fix #include<string>

the same reason #1

Author: stasysp

MainListener.hpp

@@ -0,0 +1,13 @@
+#ifndef HIGHLOADCUP_MAINLISTENER_H
+#define HIGHLOADCUP_MAINLISTENER_H
+
+#include <Poco/Util/ServerApplication.h>
+#include <iostream>
+#include <string>
+
+class MainListener final : public Poco::Util::ServerApplication {
+    virtual int main(const std::vector<std::string>& args) override;
+};
+
+
+#endif // HIGHLOADCUP_MAINLISTENER_H