#include<bits/stdc++.h>
#define int long long 
#define endl "\n"
using namespace std;
int n;
string s=" ";
string ans;
signed main (){
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	cin>>n;
	cin>>s;
	char a;
	int cnt=0;
	for(int i=0;i<n;i++){
		a=s[i];
		if(s[i]==s[i+1]){
			cnt+=1;
		}else{
			cnt+=1;
			if(cnt<10){
				char b;
				b=cnt+'0';
				ans+=b;
				ans+=a;
				cnt=0;
			}else{
				char c;
				string b;
				while(cnt!=0){
					c=cnt%10+'0';
					b.insert(0,1,c);
					cnt/=10;
				}
				ans+=b;
				ans+=a;
				cnt=0;	
			}
		}
	}
	cout<<ans<<endl;
	return 0;
}