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

template <typename Monoid>
struct Segment_Tree {
    using F = function<Monoid(Monoid, Monoid)>;
    int n;
    vector<Monoid> seg;
    const F f;
    const Monoid e1;

    // f(f(a,b),c) = f(a,f(b,c)), f(e1,a) = f(a,e1) = a

    Segment_Tree(const vector<Monoid> &v, const F &f, const Monoid &e1) : f(f), e1(e1) {
        int m = v.size();
        n = 1;
        while (n < m) n <<= 1;
        seg.assign(2 * n, e1);
        copy(begin(v), end(v), seg.begin() + n);
        for (int i = n - 1; i > 0; i--) seg[i] = f(seg[2 * i], seg[2 * i + 1]);
    }

    Segment_Tree(int m, const Monoid &x, const F &f, const Monoid &e1) : f(f), e1(e1) {
        n = 1;
        while (n < m) n <<= 1;
        seg.assign(2 * n, e1);
        vector<Monoid> v(m, x);
        copy(begin(v), end(v), begin(seg) + n);
        for (int i = n - 1; i > 0; i--) seg[i] = f(seg[2 * i], seg[2 * i + 1]);
    }

    void change(int i, const Monoid &x, bool update = true) {
        if (update) {
            seg[i + n] = x;
        } else {
            seg[i + n] = f(seg[i + n], x);
        }
        i += n;
        while (i >>= 1) seg[i] = f(seg[2 * i], seg[2 * i + 1]);
    }

    Monoid query(int l, int r) const {
        Monoid L = e1, R = e1;
        l += n, r += n;
        while (l < r) {
            if (l & 1) L = f(L, seg[l++]);
            if (r & 1) R = f(seg[--r], R);
            l >>= 1, r >>= 1;
        }
        return f(L, R);
    }

    Monoid operator[](int i) const { return seg[n + i]; }

    template <typename C>
    int find_subtree(int i, const C &check, const Monoid &x, Monoid &M, int type) const {
        while (i < n) {
            Monoid nxt = type ? f(seg[2 * i + type], M) : f(M, seg[2 * i + type]);
            if (check(nxt, x)) {
                i = 2 * i + type;
            } else {
                M = nxt;
                i = 2 * i + (type ^ 1);
            }
        }
        return i - n;
    }

    template <typename C>
    int find_first(int l, const C &check, const Monoid &x) const { // check((区間 [l,r] での演算結果), x) を満たす最小の r
        Monoid L = e1;
        int a = l + n, b = n + n;
        while (a < b) {
            if (a & 1) {
                Monoid nxt = f(L, seg[a]);
                if (check(nxt, x)) return find_subtree(a, check, x, L, 0);
                L = nxt, a++;
            }
            a >>= 1, b >>= 1;
        }
        return n;
    }

    template <typename C>
    int find_last(int r, const C &check, const Monoid &x) const { // check((区間 [l,r) での演算結果), x) を満たす最大の l
        Monoid R = e1;
        int a = n, b = r + n;
        while (a < b) {
            if ((b & 1) || a == 1) {
                Monoid nxt = f(seg[--b], R);
                if (check(nxt, x)) return find_subtree(b, check, x, R, 1);
                R = nxt;
            }
            a >>= 1, b >>= 1;
        }
        return -1;
    }
};

int main() {
    int N, M;
    cin >> N >> M;

    vector<int> A(N), B(N);
    for (int i = 0; i < N; i++) cin >> A[i];
    for (int i = 0; i < N; i++) cin >> B[i];

    set<pair<int, int>> ng; // 切られている辺
    for (int i = 0; i < M; i++) {
        int u, v;
        cin >> u >> v;
        u--, v--;
        ng.emplace(u, v);
    }

    // 補グラフを DFS して強連結成分分解する : O((N + M)(log(N) + log(M)))
    auto f = [](int a, int b) { return max(a, b); };
    auto c = [](int a, int b) { return a > b; };
    const int inf = (1 << 30) - 1;
    Segment_Tree<int> seg1(A, f, -inf), seg2(B, f, -inf);
    vector<int> vs;
    vector<int> comp(N, -1);

    function<void(int)> dfs = [&](int now) {
        if (comp[now] != -1) return;
        comp[now] = 1;
        seg1.change(now, -inf), seg2.change(now, -inf);
        int p = now + 1;
        while (p < N) {
            int np = seg2.find_first(p, c, A[now]);
            if (np >= N) break;
            if (!ng.count(make_pair(now, np))) dfs(np);
            p = np + 1;
        }
        p = now;
        while (p > 0) {
            int np = seg1.find_last(p, c, B[now]);
            if (np < 0) break;
            if (!ng.count(make_pair(np, now))) dfs(np);
            p = np;
        }
        vs.emplace_back(now);
    };

    function<void(int, int)> rdfs = [&](int now, int col) {
        if (comp[now] != -1) return;
        comp[now] = col;
        seg1.change(now, -inf), seg2.change(now, -inf);
        int p = now + 1;
        while (p < N) {
            int np = seg2.find_first(p, c, -A[now]);
            if (np >= N) break;
            if (!ng.count(make_pair(now, np))) rdfs(np, col);
            p = np + 1;
        }
        p = now;
        while (p > 0) {
            int np = seg1.find_last(p, c, -B[now]);
            if (np < 0) break;
            if (!ng.count(make_pair(np, now))) rdfs(np, col);
            p = np;
        }
    };

    for (int i = 0; i < N; i++) {
        if (comp[i] == -1) dfs(i);
    }
    fill(begin(comp), end(comp), -1);
    reverse(begin(vs), end(vs));
    for (int i = 0; i < N; i++) seg1.change(i, -A[i]), seg2.change(i, -B[i]);
    int K = 0;
    for (auto &i : vs) {
        if (comp[i] == -1) rdfs(i, K++);
    }
    vector<vector<int>> ids(K);
    for (int i = 0; i < N; i++) ids[comp[i]].emplace_back(i);

    // トポロジカルソートの逆順に見て必要な辺を調べる : O((N + M)(log(N) + log(M)) + M√M)
    vector<vector<int>> es(K);
    vector<int> deg(K, 0);
    set<int> rem;
    for (int i = 0; i < N; i++) seg1.change(i, -inf), seg2.change(i, -inf);

    for (int i = K - 1; i >= 0; i--) {
        queue<int> que;
        for (auto &e : rem) que.emplace(e);
        vector<int> check;
        for (auto &u : ids[i]) seg1.change(u, -A[u]), seg2.change(u, -B[u]);
        while (!empty(que)) {
            int j = que.front();
            que.pop();
            bool flag = false;
            // 強連結成分 i から強連結成分 j への辺があるかの判定
            for (auto &v : ids[j]) {
                int p = v + 1;
                while (p < N) {
                    int np = seg2.find_first(p, c, -A[v]);
                    if (np >= N) break;
                    if (!ng.count(make_pair(v, np))) {
                        flag = true;
                        break;
                    }
                    p = np + 1;
                }
                if (flag) break;
                p = v;
                while (p > 0) {
                    int np = seg1.find_last(p, c, -B[v]);
                    if (np < 0) break;
                    if (!ng.count(make_pair(np, v))) {
                        flag = true;
                        break;
                    }
                    p = np;
                }
                if (flag) break;
            }
            if (flag) {
                if (rem.count(j)) rem.erase(j);
                es[i].emplace_back(j);
            } else {
                check.emplace_back(j);
                for (auto &e : es[j]) {
                    if (--deg[e] == 0) que.emplace(e);
                }
            }
        }
        check.emplace_back(i);
        for (auto &j : check) {
            for (auto &e : es[j]) deg[e]++;
        }
        rem.emplace(i);
        for (auto &u : ids[i]) seg1.change(u, -inf), seg2.change(u, -inf);
    }

    vector<pair<int, int>> ans;
    for (int i = 0; i < K; i++) {
        int L = ids[i].size();
        if (L > 1) {
            for (int j = 0; j < L; j++) {
                int u = ids[i][j], v = ids[i][(j + 1) % L];
                ans.emplace_back(u, v);
            }
        }
        for (auto &j : es[i]) ans.emplace_back(ids[i][0], ids[j][0]);
    }
    cout << ans.size() << '\n';
    for (auto [u, v] : ans) cout << u + 1 << ' ' << v + 1 << '\n';
}