#include<bits/stdc++.h>
using namespace std;
#define int long long

void solve()
{
    int a, b;
    char c;
    std:: cin >> a >> c >> b;
    if(b - a >= 2)
    {
        std:: cout << "impossible" << endl;
        return ;
    }
    if(b - a == 1)
    {
        std:: cout << b << " " << a << endl;
        for(int i = 2; i <= b; i ++ )
        {
            std:: cout << 1 << " " << i << endl;
        }
        return ;
    }
    int aa = a;
    int bb = b;
    while(((b - 1) * (b) / 2 < a))
    {
        a += aa;
        b += bb;
    }
    if(b > 1000000)
    {
        std:: cout << "impossible" << endl;
        return ;       
    }
    // std:: cout << a << " " << b << endl;
    int n = b;
    vector <int> s;
    b -- ;
    while(1)
    {
        int ans = 1;
        int i;
        for(i = 1; i <= n; i ++ )
        {
            ans = i * (i + 1) / 2;
            if(ans > a)
            {
                break;
            }
        }
        s.push_back(i - 1);
        a -= (i - 1) * i / 2;
        if(a == 0)
        {
            break;
        }
    }
    int sum = 0;

    for(auto p : s)
    {
        sum += p;
    }    

    std:: cout << n << " " << sum << endl;
    int cnt = 2;
    for(auto p : s)
    {
        std:: cout << 1 << " " << cnt << endl;
        for(int i = 2; i <= p; i ++ )
        {
            std:: cout << cnt << " " << cnt + 1 << endl;
            cnt ++ ;
        }
        cnt ++ ;
    }



}
signed main()
{
	ios::sync_with_stdio(false);
	cin.tie(0), cout.tie(0);
    // int T;
    // std:: cin >> T;
    // while(T -- )
	solve();
	return 0;
}