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

int sz = 1, lev[5050] = { 1, }, mx = 0, debug = 0;
vector<pair<int, int>> ans;
void make(int l) {
    assert(l <= mx + 1);
    mx = max(mx, l);
    debug += l;
    
    lev[l] = ++sz;
    ans.push_back({ lev[l - 1], lev[l] });
}
int main() {
    cin.tie(0); ios_base::sync_with_stdio(0);
    int a = 0, b = 0, t = 0; string S; cin >> S;
    for (int i = 0; i < S.size(); i++) {
        if (S[i] == '/') ++t;
        else if (t == 0) {
            a = 10 * a + (S[i] & 15);
        }
        else {
            b = 10 * b + (S[i] & 15);
        }
    }
    if (a < b) {
        if (a != b - 1) {
            return !(cout << "impossible");
        }
        else {
            for (int i = 2; i <= b; i++) {
                make(1);
            }
            cout << sz << ' ' << ans.size() << '\n';
            for (auto [x, y] : ans) {
                cout << x << ' ' << y << '\n';
            }
        }
        return 0;
    }
    int n = (2001 + b - 1) / b * b;
    int x = n * a / b, s = 1;
    for (int i = 2; i <= n; i++) {
        if (x - s < n - i) {
            make(x - n + i + 1);
            for (int j = 0; j < n - i - 1; j++) make(1);
            break;
        }
        else {
            make(s);
            x -= s++;
        }
    }
    cout << sz << ' ' << ans.size() << '\n';
    for (auto [x, y] : ans) {
        cout << x << ' ' << y << '\n';
    }
}