#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define out(a) copy(a.begin(),a.end(),ostream_iterator<int>(cout," "))
bool vist[501][501][501];

class BearPlaysDiv2 {
public:
	string equalPiles(int A, int B, int C) {
		queue<int> que;
		int arr[] = { A, B, C }, tmp[3];
		sort(arr, arr + 3);
		for (int i = 0; i < 3; ++i)
			que.push(arr[i]);
		vist[arr[0]][arr[1]][arr[2]] = 1;
		while (que.size()) {
			for (int i = 0; i < 3; ++i) {
				arr[i] = que.front();
				que.pop();
			}
			if (arr[0] == arr[1] && arr[0] == arr[2])
				return "possible";
			for (int i = 1; i < 3; ++i) {
				memcpy(tmp, arr, sizeof tmp);
				tmp[i] -= tmp[i - 1];
				tmp[i - 1] *= 2;
				sort(tmp, tmp + 3);
				if (vist[tmp[0]][tmp[1]][tmp[2]])
					continue;
				vist[tmp[0]][tmp[1]][tmp[2]] = 1;
				for (int i = 0; i < 3; ++i)
					que.push(tmp[i]);
			}
			memcpy(tmp, arr, sizeof tmp);
			tmp[2] -= tmp[0];
			tmp[0] *= 2;
			sort(tmp, tmp + 3);
			if (vist[tmp[0]][tmp[1]][tmp[2]])
				continue;
			vist[tmp[0]][tmp[1]][tmp[2]] = 1;
			for (int i = 0; i < 3; ++i)
				que.push(tmp[i]);
		}
		return "impossible";
	}
};