// OB���h2009 Day2 C : Dial Lock

#include <iostream>

using namespace std;

int k, ans;
int cur[10], res[10];

void search(int depth, int count){
	if(depth==k){ ans = min(ans, count); return ; }
	int diff = (res[depth]-cur[depth]+10)%10;
	int tmp[10];
	for(int i=0;i<k;i++) tmp[i] = cur[i];
	if(diff == 0){
		search(depth+1, count);
	} else {
		for(int	i=depth;i<k;i++){
			cur[i] = (cur[i]+diff)%10;
			search(depth+1, count+1);
		}
		for(int i=0;i<k;i++) cur[i] = tmp[i];
	}
	return ;
}

int main(){
	while(cin >> k, k){
		long long c, a;
		cin >> c >> a;
		for(int i=0;i<k;i++){
			cur[i] = c%10; c /= 10;
			res[i] = a%10; a /= 10;
		}
		ans = k;
		search(0,0);
		cout << ans << endl;
	}
}