#include <bits/stdc++.h>
using namespace std;
using LL = long long;

#define fs first
#define sc second

const LL MOD = 1e9+7;

template<class T>bool chmax(T &a, const T &b) {
    if (a < b) { a = b; return true; }
    return false;
}
template<class T>bool chmin(T &a, const T &b) {
    if (b < a) { a = b; return true; }
    return false;
}

// input
template<typename T>
void input(T& a) { cin >> a; }
template<typename T,typename... Ts>
void input(T& a,Ts&... ts) {
    input<T>(a);
    input<T>(ts...);
}

// std::vector Declaration
template<typename T>
vector<T> make_v(size_t a) { return vector<T>(a); }
template<typename T,typename... Ts>
auto make_v(size_t a,Ts... ts) {
    return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));
}

// std::vector Initialization
template<typename T>
void fill_all(T& arr, const T& v) { arr = v; }
template<typename T, typename U>
void fill_all(T& arr, const U& v) { for (auto& i : arr) fill_all(i, v); }

// std::vector Input
template<typename T>
istream& operator>>(istream& is, vector<T>& v) {
    for (auto &e : v) {
        is >> e;
    }
    return is;
}

// std::vector Input parallel
template<typename T>
void input_at(size_t idx, T& a) {
    cin >> a[idx];
}
template<typename T, typename... Ts>
void input_at(size_t idx, T& a, Ts&... ts) {
    input_at<T>(idx, a);
    input_at<T>(idx, ts...);
}
template<typename T>
void input_parallel(T& a) {
    for (size_t idx = 0; idx < (size_t)a.size(); ++idx) {
        input_at<T>(idx, a);
    }
}
template<typename T, typename...Ts>
void input_parallel(T& a, Ts&... ts) {
    for (size_t idx = 0; idx < (size_t)a.size(); ++idx) {
        input_at<Ts...>(idx, a, ts...);
    }
}

// std::vector Debug
template<typename T>
ostream& operator<<(ostream& os, const vector<T>& v) {
    os << "[";
    bool a = 1;
    for (auto e : v) {
        os << (a ? "" : " ");
        os << e;
        a = 0;
    }
    os << "]";
    return os;
}

// std::array Debug
template<typename T, size_t n>
ostream& operator<<(ostream& os, const array<T, n>& v) {
    os << "[";
    bool a = 1;
    for (auto e : v) {
        os << (a ? "" : " ");
        os << e;
        a = 0;
    }
    os << "]";
    return os;
}

// std::deque Debug
template<typename T>
ostream& operator<<(ostream& os, const deque<T>& d) {
    os << "[";
    bool a = 1;
    for (auto e : d) {
        os << (a ? "" : " ");
        os << e;
        a = 0;
    }
    os << "]";
    return os;
}

// std::pair Debug
template<typename T, typename U>
ostream& operator<<(ostream& os, const pair<T, U>& p) {
    os << "(" << p.first << " " << p.second << ")";
    return os;
}

// std::set Debug
template<typename T>
ostream& operator<<(ostream& os, const set<T>& st) {
    os << "{";
    bool a = 1;
    for (auto e : st) {
        os << (a ? "" : " ");
        os << e;
        a = 0;
    }
    os << "}";
    return os;
}

// std::multiset Debug
template<typename T>
ostream& operator<<(ostream& os, const multiset<T>& st) {
    os << "{";
    bool a = 1;
    for (auto e : st) {
        os << (a ? "" : " ");
        os << e;
        a = 0;
    }
    os << "}";
    return os;
}

// std::map Debug
template<typename T, typename U>
ostream& operator<<(ostream& os, const map<T, U>& mp) {
    os << "{";
    bool a = 1;
    for (auto e : mp) {
        os << (a ? "" : " ");
        os << e.first << ":" << e.second;
        a = 0;
    }
    os << "}";
    return os;
}

// std::tuple Debug
template<int N, class Tuple>
void out(ostream& os, const Tuple& t){}
template<int N, class Tuple, class H, class ...Ts>
void out(ostream& os, const Tuple& t) {
    if (N) os << " ";
    os << get<N>(t);
    out<N+1,Tuple,Ts...>(os, t);
}
template<class ...Ts>
ostream& operator<<(ostream& os, const tuple<Ts...>& t) {
    os << "(";
    out<0,tuple<Ts...>,Ts...>(os, t);
    os << ")";
    return os;
}

// Debug
#define DUMP(x) cerr<<#x<<" = "<<(x)<<endl

// Weighted edge
template<typename T>
struct edge {
    int src, to;
    T cost;

    edge(int to, T cost) : src(-1), to(to), cost(cost) {}
    edge(int src, int to, T cost) : src(src), to(to), cost(cost) {}

    edge &operator=(const int &x) {
        to = x;
        return *this;
    }

    operator int() const { return to; }

    friend ostream& operator<<(ostream& os, const edge& e) {
        return os << "(" << e.src << "->" << e.to << ":" << e.cost << ")";
    }
};

template<typename T>
using Edges = vector<edge<T>>;
template<typename T>
using WeightedGraph = vector<Edges<T>>;
using UnWeightedGraph = vector<vector<int>>;
template<typename T>
using MatrixGraph = vector<vector<T>>;

int power(int x, int n) {
    int res = 1;
    while (n > 0) {
        if ((n & 1) == 1) res *= x;
        x *= x;
        n >>= 1;
    }
    return res;
}

map<char,int> mp; // 係数
map<char,int> non_zero; // 0 はダメなchar
vector<int> chars;


void dfs(int cid, int used, int total, const int size, auto& ret) {
    // if (cid == size) return total == 0;
    if (cid == size) {
        ++ret[total][used];
        return;
    }

    for (int i = non_zero[chars[cid]] ? 1 : 0; i < 10; ++i) {
        if (used & (1 << i)) continue;
        dfs(cid+1, used | (1 << i), total + mp[chars[cid]] * i, size, ret);
    }
}


int main()
{
    while (true) {
        int n; cin >> n;
        if (n == 0) {
            break;
        }
        vector<string> s(n); cin >> s;

        mp.clear();
        non_zero.clear();
        chars.clear();

        for (int i = 0; i < s.size(); ++i) {
            for (int j = 0; j < s[i].size(); ++j) {
                if (i == s.size()-1) {
                    mp[s[i][j]] -= power(10, s[i].size()-1-j);
                } else {
                    mp[s[i][j]] += power(10, s[i].size()-1-j);
                }
                if (j == 0 && s[i].size() > 1) {
                    non_zero[s[i][j]] = 1;
                }
                chars.push_back(s[i][j]);
            }
        }

        sort(chars.begin(), chars.end());
        chars.erase(unique(chars.begin(), chars.end()), chars.end());

        map<int,map<int,int>> left, right;

        int size = chars.size();
        dfs(0, 0, 0, size/2, left);
        dfs(size/2, 0, 0, size, right);

        int ans = 0;
        for (auto lp : left) {
            int n = lp.fs;
            for (auto lq : lp.sc) {
                int lused = lq.fs;
                int lcnt = lq.sc;
                for (auto rp : right[-n]) {
                    int rused = rp.fs;
                    int rcnt = rp.sc;
                    if (!(lused & rused)) {
                        ans += lcnt * rcnt;
                    }
                }
            }
        }
        cout << ans << endl;
    }

    return 0;
}



Measured memory_bytes: 12832