#include <bits/stdc++.h>

using namespace std;

const int N = 1e3+10;

int n;
char c[N], word[10] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9'};


void print(int x, char c) {
	int xx = x;

	while(xx) {
		cout << word[xx%10];
		xx /= 10;
	}

	cout << c;

}


int main() {

    // freopen("array.in", "r", stdin);
    // freopen("array.out", "w", stdout);

	cin >> n;

	for (int i = 1;i <= n;i ++) cin >> c[i];

	int it = 1, ans = 0;
	char fl = c[1];

	while (it <= n) {
		if (fl == c[it]) {
			ans ++;
			it ++;
		} else {
			print(ans, fl);
			ans = 0;
			fl = c[it];
		}
	}

	if (ans != 0) {
		print(ans, fl);
	}
   	 

    // fclose(stdin);
    // fclose(stdout);

    // system("pause");

    return 0;
	
	
}