#include<bits/stdc++.h>
#define ALL(v) std::begin(v),std::end(v)
using lint=long long;
using ld=long double;
int main(){
    std::cin.tie(nullptr);std::ios_base::sync_with_stdio(false);
    std::cout.setf(std::ios_base::fixed);std::cout.precision(15);
    lint max=100'000;
    std::vector<lint>dp(2*max+1,false);
    dp.at(max)=true;
    lint n;std::cin>>n;
    while(n--){
        lint x;std::cin>>x;
        std::vector<lint>swp(2*max+1,false);
        for(lint i=0;i<=2*max;i++){
            if(x<=i)swp.at(i-x)|=dp.at(i);
            if(i<=2*max-x)swp.at(i+x)|=dp.at(i);
        }
        swp.swap(dp);
    }
    std::cout<<(dp.at(max)?"possible":"impossible")<<'\n';
}