#pragma GCC optimize ("O3")
#pragma GCC optimize ("unroll-loops")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include <bits/stdc++.h>
typedef long long ll;
typedef long double ld;
using namespace std;
const int N = 1e5 + 5;
const int mod = 998244353;
string l, r;
string s;
int memo[N][10][2][2];
int solve(int i, int lst, bool less, bool zero) {
	if(i == s.size())
		return 1;
	int &ans = memo[i][lst][less][zero];
	if(~ans)
		return ans;
	ans = 0;
	int cur = s[i] - '0';
	for(int j = 0;j <= 9;j++) {
		if(!zero && j == lst)
			continue;
		if(!less && cur < j)
			break;
		ans += solve(i + 1, j, less | (j < cur), zero & (j == 0));
		if(ans >= mod)
			ans -= mod;
	}
	return ans;
}
bool check(string x) {
	for(int i = 1;i < x.size();i++) {
		if(x[i] == x[i - 1])
			return false;
	}
	return true;
}
int main() {
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    cin >> l >> r;
    memset(memo, -1, sizeof memo);
    s = r;
    int ans = solve(0, 0, 0, 1);
    memset(memo, -1, sizeof memo);
    s = l;
    ans -= solve(0, 0, 0, 1);
    if(ans < 0)
		ans += mod;
    ans += check(l);
    if(ans >= mod)
		ans -= mod;
    cout << ans;
    return 0;
}