How to break the loop using user input?

I am trying something like this.Its counting down seconds from 5-1.

 #include<iostream>
 #include<stdlib.h>
 #include<windows.h>
 #include<iomanip>
 using namespace std;

 int main()
 {
    for(int i=5;i>0;i--)
  {
   cout<<"\n\n\n\n\n\n";
   cout<<setw(35);
   cout<<i;
   Sleep(1000);
   system("CLS");
  }
  system("PAUSE");
}

And i trying to figure out a way to break the loop using a user input(from keyboard) to break it while its running. I have no idea about how to do this.I have heard about multi-threading. I don't even know if multi-threading has any application in my situation or not .So any ideas on how to break it in middle while its executing the loop?