#include using namespace std; #define int long long #define double long double #define FOR(i, a, b) for(int i = (a); i < (b); ++i) #define FORR(i, a, b) for(int i = (a); i > (b); --i) #define REP(i, n) for(int i = 0; i < (n); ++i) #define REPR(i, n) for(int i = n; i >= 0; i--) #define FOREACH(x, a) for(auto &(x) : (a)) #define VECCIN(x) \ for(auto &youso_ : (x)) cin >> youso_ #define bitcnt(x) __builtin_popcount(x) #define lbit(x) __builtin_ffsll(x) #define rbit(x) (64 - __builtin_clzll(x)) #define fi first #define se second #define All(a) (a).begin(), (a).end() #define rAll(a) (a).rbegin(), (a).rend() #define cinfast() cin.tie(0), ios::sync_with_stdio(false) #define PERM(c) \ sort(All(c)); \ for(bool cp = true; cp; cp = next_permutation(All(c))) #define COMB(n, k) \ for(ll bit = (1LL << k) - 1; bit < (1LL << n); bit = next_combination(bit)) #define PERM2(n, k) \ COMB(n, k) { \ vector sel; \ for(int bitindex = 0; bitindex < n; bitindex++) \ if(bit >> bitindex & 1) sel.emplace_back(bitindex); \ PERM(sel) { Printv(sel); } \ } #define MKORDER(n) \ vector od(n); \ iota(All(od), 0LL); template inline T IN() { T x; cin >> x; return (x); } inline void CIN() {} template inline void CIN(Head &&head, Tail &&... tail) { cin >> head; CIN(move(tail)...); } template inline void COUT(Head &&head) { cout << (head) << "\n"; } template inline void COUT(Head &&head, Tail &&... tail) { cout << (head) << " "; COUT(forward(tail)...); } #define CCIN(...) \ char __VA_ARGS__; \ CIN(__VA_ARGS__) #define DCIN(...) \ double __VA_ARGS__; \ CIN(__VA_ARGS__) #define LCIN(...) \ long long __VA_ARGS__; \ CIN(__VA_ARGS__) #define SCIN(...) \ string __VA_ARGS__; \ CIN(__VA_ARGS__) #define Printv(v) \ { \ FOREACH(x, v) { cout << x << " "; } \ cout << "\n"; \ } template inline void eputs(T s) { cout << s << "\n"; exit(0); } template void Fill(A (&array)[N], const T &val) { std::fill((T *)array, (T *)(array + N), val); } long long next_combination(long long sub) { long long x = sub & -sub, y = sub + x; return (((sub & ~y) / x) >> 1) | y; } // generic lambdas template #if defined(__has_cpp_attribute) && __has_cpp_attribute(nodiscard) [[nodiscard]] #elif defined(__GNUC__) && (__GNUC__ > 3 || __GNUC__ == 3 && __GNUC_MINOR__ >= 4) __attribute__((warn_unused_result)) #endif // defined(__has_cpp_attribute) && __has_cpp_attribute(nodiscard) static inline constexpr decltype(auto) fix(F &&f) noexcept { return [f = std::forward(f)](auto &&... args) { return f(f, std::forward(args)...); }; } template using PQG = priority_queue, greater>; template using PQ = priority_queue; typedef long long ll; typedef vector VL; typedef vector VVL; typedef pair PL; typedef vector VPL; typedef vector VB; typedef vector VD; typedef vector VS; const int INF = 1e9; const int MOD = 1e9 + 7; // const int MOD = 998244353; const ll LINF = 1e18; const ll dw[] = {1, 1, 0, -1, -1, -1, 0, 1}; const ll dh[] = {0, 1, 1, 1, 0, -1, -1, -1}; #define PI 3.141592653589793230 #define EPS 1e-7 bitset<10010> dp; signed main() { LCIN(N); VL W(N); VECCIN(W); ll sum = accumulate(All(W), 0LL); if(sum % 2) eputs("impossible"); dp[0] = true; REP(i, N) { dp |= dp << W[i]; } cout << (dp[sum / 2] ? "possible" : "impossible") << "\n"; }