Topo Topo

// Tested by zydhanlinnar11 on May 28, 2022
#include <iostream>
#include <vector>
#include <stack>
#include <cassert>
using namespace std;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef stack<int> si;

bool dfs(vvi &adjList, vi &state, si &vertex, int dst) {
    if(state[dst] == 1)
        return false;
    if(state[dst] == 2)
        return true;
    state[dst] = 1;
    bool ret = true;
    for(int i=0; i < adjList[dst].size() && ret; i++)
        ret &= dfs(adjList, state, vertex, adjList[dst][i]);
    state[dst] = 2;
    vertex.push(++dst);
    return ret;
}

bool topsort(vvi &adjList, vi &state, si &vertex, int n) {
    for(int i=0; i<n; i++)
        if(state[i] != 2 && !dfs(adjList, state, vertex, i))
            return false;
    return true;
}

int main() {
    #ifdef ZYD_WSL
        freopen("/home/zydhanlinnar11/prakfinal-qa/in", "r", stdin);
    #endif
    ios_base::sync_with_stdio(false); cin.tie(NULL);
    int n, m;
    cin>>n>>m;
    assert(n == (int)1e5 && m == (int)1e5);
    assert(1 <= n && n <= (int)1e5);
    assert(1 <= m && m <= (int)1e5);
    vvi adjList(n); vi state(n, 0); si vertex;
    for(int i=0; i<m; i++) {
        int src, dst;
        cin>>src>>dst;
        assert(1 <= src && src <= n);
        assert(1 <= dst && dst <= n);
        src--, dst--;
        adjList[src].push_back(dst);
    }
    if(topsort(adjList, state, vertex, n))
        for(int i=0; i<n; i++) {
            cout<<vertex.top()<<" \n"[i == n - 1];
            vertex.pop();
        }
    else cout<<"-1\n";
    return 0;
}