#include <iostream>
#include <string>
using namespace std;
void task1()
{
    int n ,a,b;
    int countOfMaterial=0;
     cin>>n>>a>>b;
    for(int i = 0 ; i < n; i++)
    {
        countOfMaterial = countOfMaterial+a*b;
    }
    cout<<countOfMaterial*2<<endl;
}
void task2()
{
    int a,  b;
    int countOfFuses=0;
    cin>>a>>b;
    for(int i = a; i <=b;i++)
    {
        if(i%2!=0) countOfFuses++;
    }
    cout<<countOfFuses<<endl;
}
void task3()
{
    int length;
    int countOfDigits=1;
    string input;
    string output;
    cin>>length>>input;



    for(int i= 0 ; i < length-1; i++)
    {

      if(input[i] == input[i+1])countOfDigits++;
      if(input[i] != input[i+1])
      {

        output=output+to_string(countOfDigits)+input[i];

      }
    }
    cout<<output;

}
void task4()
{

}
void task5()
{

}
int main()
{
//task1();
//task2();
task3();
return 0;
}