#include <cstdio>
#include <vector>
#include <algorithm>
#include <cstring>

using namespace std;

const int NMAX = 255;
const int MMAX = 1500;

int last_index;
int Min[NMAX+5];
int ind[NMAX+5];
bool instack[NMAX+5];
int st[NMAX+5], Size;

int indeg[NMAX+5];
bool a[NMAX+5][NMAX+5];
vector <int> g[NMAX+5];
bool vis[NMAX+5];
vector <int> List;
vector <int> cuplaj[NMAX+5];
int left[NMAX+5], right[NMAX+5];
int Comp[NMAX+5];

vector <int> v[NMAX+5];

int comp;
vector <int> ans[NMAX+5];

void dfs(int nod)
{
    ind[nod] = last_index;
    Min[nod] = last_index;
    instack[nod] = true;
    last_index++;
    st[Size++] = nod;
    for(int i=0; i<v[nod].size(); i++)
    {
        if(ind[v[nod][i]] == 0)
        {
            dfs(v[nod][i]);
            Min[nod] = min(Min[nod], Min[v[nod][i]]);
        }
        else if(instack[v[nod][i]])
        {
            Min[nod] = min(Min[nod], Min[v[nod][i]]);
        }
    }
    if(Min[nod] == ind[nod])
    {
        int top;
        comp++;
        do
        {
            Size--;
            top = st[Size];
            instack[top] = false;
            ans[comp].push_back(top);
        }
        while(Size>=0 && top!=nod);
    }
}

void dfs_cuplaj(int nod)
{
    vis[nod] = true;
    if(g[nod].size() == 0)
    {
        List.push_back(nod);
        return;
    }
    for(int i=0; i<g[nod].size(); i++)
        if(!vis[g[nod][i]])
        {
            dfs_cuplaj(g[nod][i]);
        }
}

bool pairUp(int node)
{
    if(vis[node])return false;
    vis[node] = true;
    for(int i=0; i<cuplaj[node].size(); i++)
    {
        int right_node = cuplaj[node][i];
        if(left[right_node] == 0 || pairUp(left[right_node]) == true)
        {
            left[right_node] = node;
            right[node] = right_node;
            return true;
        }
    }
    return false;
}

int main()
{
    freopen("plan.in", "r", stdin);
    freopen("plan.out", "w", stdout);
    int n, m;
    scanf("%d%d", &n, &m);
    for(int i=0; i<m; i++)
    {
        int x, y;
        scanf("%d%d", &x, &y);
        if(x!=y) v[x].push_back(y);
    }
    last_index = 1;
    for(int i=1; i<=n; i++)
        if(ind[i] == 0)
            dfs(i);
    if(comp == 1)
    {
        printf("0\n");
        return 0;
    }
    for(int i=1; i<=comp; i++)
    {
        for(int j=0; j<ans[i].size(); j++)
            Comp[ans[i][j]] = i;
    }
    for(int i=1; i<=n; i++)
        for(int j=0; j<v[i].size(); j++)
            a[Comp[i]][Comp[v[i][j]]] = true;
    for(int i=1; i<=comp; i++)
        for(int j=1; j<=comp; j++)
            if(i!=j && a[i][j])
            {
                g[i].push_back(j);
                indeg[j]++;
            }
    int nrleft = 0;
    for(int i=1; i<=comp; i++)
        if(indeg[i] == 0)
            nrleft++;
    int nrright = 0;
    for(int i=1; i<=comp; i++)
        if(g[i].size() == 0)
            nrright++;
    printf("%d\n", max(nrleft, nrright));
    for(int i=1; i<=comp; i++)
        if(indeg[i] == 0)
        {
            memset(vis, 0, sizeof(vis));
            List.clear();
            dfs_cuplaj(i);
            for(int j=0; j<List.size(); j++)
                cuplaj[i].push_back(List[j]);
        }
    bool ok = true;
    while(ok)
    {
        ok = false;
        memset(vis, 0, sizeof(vis));
        for(int i=1; i<=comp; i++)
            if(right[i] == 0 && pairUp(i)) ok = true;
    }
    int c = -1, japca;
    for(int i=1; i<=comp; i++)
        if(indeg[i] == 0 && right[i]!=0)
        {
            if(c!=-1) printf("%d %d\n", ans[c][0], ans[i][0]);
            else japca = i;
            c = right[i];
        }
    printf("%d %d\n", ans[c][0], ans[japca][0]);
    for(int i=1; i<=comp; i++)
        if(indeg[i] == 0 && right[i] == 0)
            printf("%d %d\n", ans[japca][0], ans[i][0]);
    for(int i=1; i<=comp; i++)
        if(g[i].size() == 0 && left[i] == 0)
            printf("%d %d\n", ans[i][0], ans[japca][0]);
    return 0;
}