#include <vector>
#include <iostream>
#include <stdint.h>

using namespace std;

typedef uint32_t u32;
struct s_visited
{
    u32 a;
    u32 b;
    u32 index;
};

struct s_connection
{
    u32 a;
    u32 b;
};
vector<s_connection> connections = {};

bool has_path(u32 a, u32 b, vector<s_visited>* visited)
{
    for(u32 i = 0; i < connections.size(); i++) {
        s_connection c = connections[i];

        if((c.a == a && c.b == b) || (c.b == a && c.a == b)) { return true; }
        bool skip = false;
        for(u32 j = 0; j < visited->size(); j++) {
            s_visited v = visited->at(j);
            if(v.index == i && (v.a == a && v.b == b) || (v.b == a && v.a == b)) {
                skip = true;
                break;
            }
        }
        if(skip) { continue; }
        visited->push_back({a, b, i});

        if(c.a == a) {
            if(has_path(c.b, b, visited)) { return true; }
        }

        if(c.b == a) {
            if(has_path(c.a, b, visited)) { return true; }
        }
    }

    return false;
}

int main()
{
    u32 cities;
    u32 roads;
    cin >> cities >> roads;
    for(u32 i = 0; i < roads; i++) {
        u32 a;
        u32 b;
        cin >> a >> b;
        connections.push_back({a, b});
    }

    u32 curr = 1;
    vector<s_connection> added = {};
    for(u32 i = 0; i < cities; i++) {
        u32 ii = i + 1;
        if(curr == ii) { continue; }
        vector<s_visited> visited = {};
        if(!has_path(curr, ii, &visited)) {
            connections.push_back({curr, ii});
            added.push_back({curr, ii});
        }
        curr += 1;
    }
    printf("%zu\n", added.size());
    for(u32 i = 0; i < added.size(); i++) {
        printf("%i %i\n", added[i].a, added[i].b);
    }
    return 0;
}