#pragma GCC optimize("Ofast")
#pragma GCC optimize("O3")

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

#define el '\n'
#define F first
#define S second

typedef long long ll;
typedef long double ld;

bool multipleTestCases = 0, sublime = 0;
const int N = 2e3 + 5, INF = 1e9 + 5, mod = 1e9 + 7, LOG = 22, SQ = 500;

int sum, id, rem;
vector<pair<int, int>> edges;

void dfs(int u, int d) {
    while (sum >= d + 1 && sum - d - 1 >= rem - 1)
        sum -= d + 1, rem--, edges.emplace_back(u, id++), dfs(id - 1, d + 1);
}

void doWork() {
    char x, y;
    cin >> x >> y >> y;

    int a = x - '0', b = y - '0';

    if (a < b - 1)
        return cout << "impossible", void();

    int n;
    for (n = b; ; n += b) {
        if (n * (n - 1) / 2 >= a * n / b) {
            id = 2, sum = a * n / b, rem = n - 1;

            dfs(1, 0);

            cout << n << ' ' << edges.size() << el;

            for (auto &i: edges)
                cout << i.first << ' ' << i.second << el;

            return;
        }
    }
}

signed main() {
#ifdef ONLINE_JUDGE
    ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
#endif
#ifndef ONLINE_JUDGE
    if (sublime) {
        freopen("input.txt", "r", stdin);
        freopen("output.txt", "w", stdout);
    }
#endif
    int tests = 1;
    if (multipleTestCases) {
        cin >> tests;
    }
    for (int tc = 1; tc <= tests; tc++) {
        doWork();
    }
}