#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>

#define el '\n'
#define FIO ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);

using namespace std;
using namespace __gnu_pbds;

typedef long long ll;
typedef long double ld;
typedef complex<ld> pt;
typedef unsigned long long ull;

template<typename T, typename X>
using hashTable = gp_hash_table<T, X>;
template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T>
using ordered_multiset = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;

// mt19937_64 for long long
mt19937 rng(std::chrono::system_clock::now().time_since_epoch().count());

const int M = 1e6;


void doWork()
{
    char c;
    int a, b;
    cin >> a >> c >> b;

    int n, sum;
    for(n = b; n <= M; n += b)
    {
        sum = n / b * a;
        if(1LL * n * (n - 1) / 2 < sum)
            continue;


        int node = 3;
        sum -= (n - 1);
        if(sum < 0)
            continue;
        
        vector<pair<int, int>> e;

        e.emplace_back(1, 2);
        for(int dep = 1; node <= n; dep++, node++)
        {
            if(sum - dep >= 0)
                sum -= dep, e.emplace_back(node - 1, node);
            else
            {
                e.emplace_back(sum + 1, node), node++;
                while(node <= n)
                    e.emplace_back(1, node++);
                break;
            }
        }
        cout << n << ' ' << e.size() << '\n';
        for(auto &[u, v]: e)
            cout << u << ' ' << v << '\n';

        return;
    }
    cout << "impossible";
}

signed main()
{
    FIO
    int T = 1;
//    cin >> T;
    for(int i = 1; i <= T; i++)
        doWork();
}