#pragma comment(linker, "/STACK:64000000")
#include <iostream>
#include <vector>
#include <map>
using namespace std;
#define INF 1000*1000*1000
vector<pair<int,int> > line;
int m;
int path[60002][4] = {0};
int dp[60002];
int dfs(int k)
{
    if(dp[k] != -1)
        return dp[k];

    int a = line[k].first;
    int b = line[k].second;

    if(a <= m && b >= m)
        return 0;

    int mn = INF;
    for (int i = 0; i < line.size(); i++)
    {
        int L = line[i].first;
        int R = line[i].second;
        if(L > a && R > b && L <= b)
        {
            int r = dfs(i) + 1;
            if( r < mn)
            {
                mn = r;
                path[k][0] = L;
                path[k][1] = R;
                path[k][2] = i;
            }
        }
    }
    return dp[k] = mn;
}
int main()
{
    memset(dp,255,sizeof dp);
    //freopen ("input.txt","r",stdin);
    scanf ("%d",&m);
    line.push_back(make_pair(-666666,0));
    while(1)
    {
        int a,b;
        scanf ("%d%d",&a,&b);
        if(a == 0 && b == 0)
            break;
        line.push_back(make_pair(a,b));
    }
    int ans = dfs(0);
    if(ans == INF)
        puts ("No solution");
    else
    {
        printf ("%d\n",ans);
        int j = 0;
        for (int i = 0; i < ans; i++)
        {
            printf ("%d %d\n",path[j][0],path[j][1]);
            j = path[j][2];
        }
    }
    return 0;
}