Timer in the game C++

[Kalnuose]

I am begginer.. and I have some kind of trouble with making my game. I don't know how to count time while "person is thinking" from one pressed enter to next.. Help

THIS IS THE GAME:

  #include <iostream>
#include <cstdlib> // for rand()
#include <ctime>
#include <fstream>
#include <iomanip>
#include <cmath>
#include <stdio.h>      /* printf */
#include <time.h>

using namespace std;
bool skaitmenys[10];
int main()
{
   time_t rawtime;
   time (&rawtime);

   //radimas random skaiciaus
   int skaitmuo, suma =0, x=0;
    srand (time(NULL));
    while(suma!=4)
    {
        skaitmuo = rand() % 10 + 1;
        if(skaitmuo!=10)
        if(!skaitmenys[skaitmuo])
        { skaitmenys[skaitmuo] = true; suma++; }
    }
    for(int i = 0; i < 10; i++)
    if(skaitmenys[i])
    x = x*10 + i;

   //x skaiciaus skaidymas i skaitmenis
   int a1, b1, c1, d1;
   d1=x%10;
   c1=x/10%10;
   b1=x/100%10;
   a1=x/1000%10;
   //skaiciaus spejimas
   int y, i; //a = skaicius vienodu skaiciu; b = skaicius skaiciu savo vietoje
   cout << "Iveskite skaiciu:" << endl;
   i=0;
   while(x != y)
   {
   cin >> y;
   //y skaiciaus skaidymas i skaitmenis
   int a2, b2, c2, d2;
   d2=y%10;
   c2=y/10%10;
   b2=y/100%10;
   a2=y/1000%10;
   i++; //spejimu kartai
   //speliojimo rezultatai
   int m=0, n=0;
   if (a1==a2) {m++; n++;}
   if (a1==b2) {m++;}
   if (a1==c2) {m++;}
   if (a1==d2) {m++;}

   if (b1==b2) {m++; n++;}
   if (b1==a2) {m++;}
   if (b1==c2) {m++;}
   if (b1==d2) {m++;}

   if (c1==c2) {m++; n++;}
   if (c1==a2) {m++;}
   if (c1==b2) {m++;}
   if (c1==d2) {m++;}

   if (d1==d2) {m++; n++;}
   if (d1==a2) {m++;}
   if (d1==b2) {m++;}
   if (d1==c2) {m++;}
   cout <<" "<< m <<":"<< n<<endl;
   }

   //isprendete
   cout << "You have solved. Result " << i << " times" << s << endl;
   
	return 0;
}