string转int

#include<iostream>
#include<sstream>
#include<string>
using namespace std;
int main()
{
	/*stringstream ss; 
	string s[4];
    int n;
	cin>>s[0];
	ss<<s[0];
	ss>>n;
	cout<<4*n;*/
	string s[4];
	cin>>s[0];
	cout<<4*stoi(s[0])<<endl;
 }