#include<iostream>
#include<cstring>
#include<vector>
#include<array>
#include<cassert>
#include<climits>
using namespace std;
using LL = long long;
const int mod = 998244353;

void add(int &a, int b){
    a += b;
    if (a >= mod) a -= mod;
}

int mul(int a, int b){
    return 1LL * a * b % mod;
}

int C[51][51];

int a[1010], b[1010];

// bool v[1010][10][2][2];
// array<int, 50> f[1010][10][2][2];
bool v[1010][10];
array<int, 50> f[1010][10];

int pow10[1010], pows[50], inv[50];

unsigned long long tmp[50];
const unsigned long long lim = ULLONG_MAX - 1e18;

int k;

void update(array<int, 50> &ans, array<int, 50> t, int val){
    pows[0] = 1;
    for(int i = 1; i < k; i++) pows[i] = mul(pows[i - 1], val);
    memset(tmp, 0, sizeof tmp);
    for(int i = 0; i < k; i++){
        for(int j = 0; j <= i; j++){
            tmp[i] += 1ULL * mul(pows[j], t[i - j]) * C[i][j];
            if (tmp[i] > lim){
                tmp[i] %= mod;
            }
        }
    }
    for(int i = 0; i < k; i++){
        add(ans[i], tmp[i] % mod);
    }
}

array<int, 50> e;

// 当前位数, lim, 是否需要往上借位, 是否全是前导零

array<int, 50> dfs(int u, int last, bool lim, bool lead){
    if (u == 0){
        return e;
    }
    if (lead) last = 9;
    if (!lead and !lim and v[u][last]) return f[u][last];
    int down = lim ? b[u] : 0;
    int up = last;
    array<int, 50> ans{};
    for(int i = down; i <= up; i++){
        update(ans, dfs(u - 1, i, lim and (i == down), lead and (i == 0)), mul(i, pow10[u - 1]));
    }
    if (!lead and !lim){
        v[u][last] = true;
        f[u][last] = ans;
    }
    return ans;
}

int main(){

#ifdef LOCAL
    freopen("data.in", "r", stdin);
    freopen("data.out", "w", stdout);
#endif

    cin.tie(0);
    cout.tie(0);
    ios::sync_with_stdio(0);

    for(int i = 0; i <= 50; i++){
        for(int j = 0; j <= i; j++){
            if (!j) C[i][j] = 1;
            else C[i][j] = (C[i - 1][j - 1] + C[i - 1][j]) % mod;
        }
    }

    inv[1] = 1;
    for(int i = 2; i < 50; i++){
        inv[i] = mul(mod - mod / i, inv[mod % i]);
    }

    string L, R;
    cin >> L >> R;
    int pos = R.size() - 1;
    while(pos >= 0 and R[pos] == '9') pos--;
    if (pos == -1){
        R = "1" + string(R.size(), '0');
    }
    else{
        R[pos] += 1;
        for(int i = pos + 1; i < R.size(); i++){
            R[i] = '0';
        }
    }

    cin >> k;
    e[0] = 1;
    pow10[0] = 1;
    for(int i = 1; i < 1010; i++){
        pow10[i] = mul(pow10[i - 1], 10);
    }

    int c[51]{};
    c[0] = 1;
    for(int j = 0; j < k - 1; j++){
        int nc[51]{};
        for(int t = 0; t < 50; t++){
            add(nc[t + 1], c[t]);
            add(nc[t], mul(c[t], mod - j));
        }
        swap(c, nc);
    }

    int sum = 0;
    for(int cnt = 0; cnt <= k; cnt++){
        memset(b, 0, sizeof b);
        for(int i = 0; i < L.size(); i++){
            b[L.size() - i] += (L[i] - '0') * (k - cnt);
        }
        for(int i = 0; i < R.size(); i++){
            b[R.size() - i] += (R[i] - '0') * cnt;
        }
        for(int i = 1; i + 1 < 1010; i++){
            b[i + 1] += b[i] / 10;
            b[i] %= 10;
        }

        int t = 0;
        for(int i = R.size() + 3; i >= 1; i--){
            t = (t * 10LL + b[i]) % mod;
        }
        t = (mod - t + k - 1) % mod;

        int sign = mul(cnt % 2 == 0 ? 1 : mod - 1, C[k][cnt]);

        array<int, 50> ans{};
        update(ans, dfs(R.size() + 3, 9, true, true), t);
        int ss = 0;
        for(int i = 0; i < k; i++){
            add(ss, mul(ans[i], c[i]));
        }
        for(int i = 1; i <= k - 1; i++){
            ss = mul(ss, inv[i]);
        }
        add(sum, mul(sign, ss));
    }
    cout << sum << '\n';

}