#include <iostream>
using namespace std;

int main() {

	std::string input = "Sin(3x)";

	// obtain inner content
	unsigned open  = input.find("(") + 1;
	unsigned close = input.find(")") - 1;
	string output = input.substr(open, close - open);

	printf("%s\n", output.c_str());

	system("pause");
	return 0;

};