#include <bits/stdc++.h>

using namespace std;
typedef long long int ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef long double ld;
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define nl "\n"
#define all(v) v.begin(),v.end()

ll n, m, t, a, b, c;

ll par[100005];

int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	char tt;
	cin >> a >> tt >> b;
	if (a < b) {
		if (a != b-1) cout << "impossible";
		else {
			cout << b << " " << b - 1 << nl;
			for (int i=1; i<b; i++) {
				cout << 1 << " " << i + 1 << nl;
			}
		}
		return 0;
	}
	
	ll k = 1;
	
	while (true) {
		ll x = k * b;
		if (x * (x-1) / 2 >= k * a) break;
		k++;
	}

	ll x = k * b;
	
	ll cur = x * (x-1) / 2;
	ll tmp = a * k;
	
	for (int i=1; i<x; i++) {
		par[i+1] = i;
	}
	
	ll cur1 = x;
	
	while (cur > tmp) {
		if (par[cur1] == 1) cur1--;
		else {
			par[cur1]--;
			cur--;
		}
	}
	
	cout << x << " " << x - 1 << nl;
	for (int i=2; i<=x; i++) {
		cout << i << " " << par[i] << nl;
	}
}