#include"bits/stdc++.h"
#define int long long
//ten year OI -> NULL
//no ll meet grandfather
using namespace std;
inline int read(){
	int xr = 0, f = 1;
	char cr;
	while (cr = getchar(), cr < '0' or cr > '9')
	{
		if (cr == '-')
		{
			f = -1;
		}
	}
	while (cr >= '0' and cr <= '9')
	{
		xr = (xr << 3) + (xr << 1) + (cr ^ 48);
		cr = getchar();
	}
    return xr * f;
}	
int n;
string s;
signed main(){
	n = read();
	cin >> s;
	int len = 1;
	for(int i = 0; i < s.size(); i = -~i){
		if(s[i] == s[i + 1]){
			len = -~len;
		}else{
			cout << len << s[i];
			len = 1;
		}
	}
    return 0;
}