#include<cstdio>
using namespace std;
inline int read()
{
	char c=getchar();int x=0,f=1;
	while(c<'0'||c>'9')
	{
		if(c=='-') f=-1;
		c=getchar();
	}
	for(;c>='0'&&c<='9';c=getchar()) x=x*10+c-'0';
	return x*f;
}
int n;
char a[101111];
int main()
{
//	freopen(".in","r",stdin);
//	freopen(".out","w",stdout);
	n=read();
	scanf("%s",a+1);
	int cnt=1,lst=a[1]-'0';
	for(int i=2;i<=n;i++)
		if(a[i]-'0'!=lst)
			printf("%d%d",cnt,lst),cnt=1,lst=a[i]-'0';
		else cnt++;
	printf("%d%d",cnt,lst);
	return 0;
}