#include <bits/stdc++.h>
using namespace std; 
typedef unsigned long long u64; 
const u64 B = 10007; 

int n, PP, M, pw[10]; 
mt19937_64 Rand(time(0)); 
u64 ha[1005], vl[1005], p[2005]; 
vector<char> ans[2005]; 
set<int> Q[1005]; 
map<u64, vector<int>> mp; 
int fa[1005]; 
int find(int x) { return fa[x] == x ? x : fa[x] = find(fa[x]); }

int main(void) {
    ios::sync_with_stdio(0); 
    for (int i = p[0] = 1; i <= 2000; ++i) p[i] = p[i - 1] * B; 
    for (int i = pw[0] = 1; i <= 10; ++i) pw[i] = pw[i - 1] * 3; 

    cin >> n >> PP >> M; 
    for (int i = 1; i <= n; ++i) ans[i].push_back('A'), ans[i + n].push_back('B'); 
    for (int i = 1; i <= n; ++i) vl[i] = Rand(); 
    while (PP--) {
        int x, y; cin >> x >> y; 
        if (x > y) swap(x, y); 
        Q[x].insert(y); 
        ha[x] += vl[y - n]; 
    }
    for (int i = 1; i <= n; ++i) fa[i] = i; 
    for (int i = 1; i <= n; ++i) for (int j = i + 1; j <= n; ++j)
        if (ha[i] == ha[j]) fa[find(j)] = find(i); 

    for (int i = 1; i <= n; ++i) if (find(i) == i) {
        for (int j = 1; j <= n; ++j) 
            if (find(i) == find(j)) ans[j].push_back('A'); 
            else ans[j].push_back('B'); 

        for (int j = 1; j <= n; ++j)
            if (Q[i].count(j + n)) ans[j + n].push_back('A'); 
            else ans[j + n].push_back('C'); 
    }

    for (int i = 1; i <= n * 2; ++i) {
        u64 val = 0; 
        for (int j = 0; j < ans[i].size(); ++j)
            val = val * B + ans[i][j]; 
        mp[val].push_back(i); 
    }
    int mx = 0; 
    for (const auto& [x, y] : mp) mx = max(mx, int(y.size())); 
    cerr << mx << "\n"; 

    int t = 0, res = 1; 
    while (res < mx) res *= 3, ++t; 
    for (const auto& [x, y] : mp) 
        for (int i = 0; i < y.size(); ++i)
            for (int j = t - 1; j >= 0; --j)
                ans[y[i]].push_back(char((i / pw[j]) % 3 + 'A')); 

    cout << ans[1].size() << '\n'; 
    for (int i = 1; i <= n * 2; ++i) {
        for (int j = 0; j < ans[1].size(); ++j) cout << ans[i][j]; 
        cout << '\n'; 
    }
    return 0;
}