#include <bits/stdc++.h>

using i64 = long long;
using u64 = unsigned long long;
using u32 = unsigned;
using u128 = unsigned __int128;

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    
    int n, p, M;
    std::cin >> n >> p >> M;
    std::vector g(n, std::vector<int>(n)), gT(n, std::vector<int>(n));
    for (int i = 0; i < p; i++) {
        int a, b;
        std::cin >> a >> b;
        a--;
        b--;
        b -= n;
        g[a][b] = 1;
        gT[b][a] = 1;
    }
    
    bool swapped = false;
    int l = std::set(g.begin(), g.end()).size();
    int r = std::set(gT.begin(), gT.end()).size();
    if (l > r) {
        std::swap(l, r);
        std::swap(g, gT);
        swapped = true;
    }
    
    std::map<std::vector<int>, std::vector<int>> vec;
    std::map<std::vector<int>, std::vector<int>> vecb;
    for (int i = 0; i < n; i++) {
        vec[g[i]].push_back(i);
        vecb[gT[i]].push_back(i);
    }
    
    std::vector<std::string> ans(2 * n);
    int maxa = 0, maxb = 0;
    for (const auto &[b, a] : vec) {
        maxa = std::max(maxa, int(a.size()));
    }
    for (const auto &[a, b] : vecb) {
        maxb = std::max(maxb, int(b.size()));
    }
    
    bool special3 = (maxa == 3 && l == n - 2 && l == r && maxb == maxa);
    bool special5 = (maxa == 5 && l == n - 4 && l == r && maxb == maxa);
    
    for (const auto &[b, a] : vec) {
        if (special3 && a.size() == 3) {
            for (auto mask : {3, 5}) {
                for (int i = 0; i < n; i++) {
                    ans[i] += 'A';
                    ans[n + i] += 'B';
                }
                for (int i = 0; i < a.size(); i++) {
                    if (mask >> i & 1) {
                        ans[a[i]].back() = 'C';
                    }
                }
                for (int i = 0; i < n; i++) {
                    if (b[i]) {
                        ans[n + i].back() = 'C';
                    }
                }
            }
            continue;
        }
        if (special5 && a.size() == 5) {
            for (auto mask : {7, 13, 25}) {
                for (int i = 0; i < n; i++) {
                    ans[i] += 'A';
                    ans[n + i] += 'B';
                }
                for (int i = 0; i < a.size(); i++) {
                    if (mask >> i & 1) {
                        ans[a[i]].back() = 'C';
                    }
                }
                for (int i = 0; i < n; i++) {
                    if (b[i]) {
                        ans[n + i].back() = 'C';
                    }
                }
            }
            continue;
        }
        for (int i = 0; i < n; i++) {
            ans[i] += 'A';
            ans[n + i] += 'B';
        }
        for (auto i : a) {
            ans[i].back() = 'C';
        }
        for (int i = 0; i < n; i++) {
            if (b[i]) {
                ans[n + i].back() = 'C';
            }
        }
    }
    
    int ka = std::__lg(2 * maxa - 1);
    int kb = std::__lg(2 * maxb - 1);
    
    if (!special3 && !special5) {
        for (int i = 0; i < ka; i++) {
            for (int i = 0; i < n; i++) {
                ans[i] += 'A';
                ans[n + i] += 'B';
            }
            for (const auto &[b, a] : vec) {
                for (int j = 0; j < a.size(); j++) {
                    if (j >> i & 1) {
                        ans[a[j]].back() = 'C';
                    }
                }
            }
        }
    }
    for (int i = 0; i < kb; i++) {
        for (int i = 0; i < n; i++) {
            ans[i] += 'A';
            ans[n + i] += 'B';
        }
        for (const auto &[a, b] : vecb) {
            for (int j = 0; j < b.size(); j++) {
                if (j >> i & 1) {
                    ans[n + b[j]].back() = 'C';
                }
            }
        }
    }
    if (r == n) {
        for (int i = 0; i < n; i++) {
            ans[i] += 'A';
            ans[n + i] += 'B';
        }
    }
    
    if (swapped) {
        std::rotate(ans.begin(), ans.begin() + n, ans.end());
    }
    std::cout << ans[0].size() << "\n";
    for (const auto &s : ans) {
        std::cout << s << "\n";
    }
    
    return 0;
}