#define  _CRT_SECURE_NO_WARNINGS
#pragma comment (linker, "/STACK:526000000")

#include "bits/stdc++.h"

using namespace std;
typedef string::const_iterator State;
#define eps 1e-11L
#define MAX_MOD 1000000007LL
#define GYAKU 500000004LL

#define MOD 998244353LL
#define seg_size 262144 * 4LL
#define pb push_back
#define mp make_pair
typedef long long ll;
#define REP(a,b) for(long long (a) = 0;(a) < (b);++(a))
#define ALL(x) (x).begin(),(x).end()

unsigned long xor128() {
	static unsigned long x = 123456789, y = 362436069, z = 521288629, w = time(NULL);
	unsigned long t = (x ^ (x << 11));
	x = y; y = z; z = w;
	return (w = (w ^ (w >> 19)) ^ (t ^ (t >> 8)));
}
void init() {
	iostream::sync_with_stdio(false);
	cout << fixed << setprecision(20);
}

#define int ll

int dfs(string a,string b,int c) {
	if (c >= a.length()) return 0;
	if (a[c] == b[c]) {
		return dfs(a, b, c + 1);
	}
	int target = b[c] - a[c] + 10;
	target %= 10;
	int ans = 1e9;
	for (int q = c; q < a.length(); ++q) {
		a[q] += target;
		if (a[q] > '9') a[q] -= 10;
		ans = min(ans, dfs(a, b, c + 1) + 1);
	}
	return ans;
}

void solve(){
	while (true) {
		int k;
		cin >> k;
		if (k == 0)return;
		string a, b;
		cin >> a >> b;
		cout << dfs(a,b,0) << endl;
	}
}

#undef int

int main() {
	init();
	solve();
}
