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

#define fs first
#define sc second

const LL MOD = 1e9+7;
const double EPS = 1e-10;

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;
}

// 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 Declaration and Initialization
template<typename T>
vector<T> make_vector(size_t a, T x) { return vector<T>(a, x); }
template<typename T, typename U, typename... Ts>
auto make_vector(size_t a, U b, Ts... ts) {
    return vector<decltype(make_vector<T>(b,ts...))>(a,make_vector<T>(b,ts...));
}

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

// 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>>;

template< typename flow_t >
struct FordFulkerson {
    struct edge {
        int to;
        flow_t cap;
        int rev;
        bool isrev;
        int id;
        edge(int to, flow_t cap, int rev, bool isrev, int id) :
            to(to), cap(cap), rev(rev), isrev(isrev), id(id) {}
        friend ostream& operator<<(ostream& os, const edge& e) {
            return os << "{to:" << e.to << ",cap:" << e.cap
                      << ",isrev:" << e.isrev << "}";
        }
    };

    vector<vector<edge>> g;
    vector<int> used;
    const flow_t inf;
    int timestamp;

    FordFulkerson(int n) : inf(numeric_limits<flow_t>::max()), timestamp(0) {
        g.resize(n);
        used.assign(n, -1);
    }

    void add_edge(int src, int to, flow_t cap, int id) {
        g[src].emplace_back(to, cap, (int)g[to].size(), false, id);
        g[to].emplace_back(src, cap, (int)g[src].size()-1, true, id);
    }

    flow_t dfs(int v, const int t, flow_t flow) {
        if(v == t) return flow;
        used[v] = timestamp;
        for(auto &e : g[v]) {
            if(e.cap > 0 && used[e.to] != timestamp) {
                flow_t d = dfs(e.to, t, min(flow, e.cap));
                if(d > 0) {
                    e.cap -= d;
                    g[e.to][e.rev].cap += d;
                    return d;
                }
            }
        }
        return 0;
    }

    flow_t max_flow(int s, int t) {
        flow_t flow = 0;
        for(flow_t f; (f = dfs(s, t, inf)) > 0; timestamp++) {
            flow += f;
        }
        return flow;
    }
};

int main()
{
    int n, m; cin >> n >> m;

    FordFulkerson<int> ford(n);
    for (int i = 0; i < m; ++i) {
        int u, v; cin >> u >> v; --u, --v;
        ford.add_edge(u, v, 1, i);
    }

    int S, T; cin >> S >> T; --S, --T;

    int flow = ford.max_flow(S, T);
    cout << flow << endl;

    vector<int> flip;
    for (auto v : ford.g) {
        for (auto e : v) {
            if (e.isrev && e.cap == 0) {
                flip.push_back(e.id);
            }
        }
    }

    cout << flip.size() << endl;
    for (auto i : flip) {
        cout << i+1 << endl;
    }

    return 0;
}



Measured memory_bytes: 3248