#include <cstdio>

 #include <cstring>

 #include <algorithm>

 #include <iostream>

 using namespace std;

 const int v =  + ;

 const int MaxN =  + ;

 int N, sum, num[MaxN], dp[][v];

 int main() {

     int i, j, k;

     cin >> N;

     for(i = ; i < N; ++i) {

         cin >> num[i];

         sum += num[i];

     }

     memset(dp, -, sizeof(dp));

     dp[][] = ;

     int a;

     for(i = ; i < N; ++i) {

         a = i % ;

         memset(dp[a], -, sizeof(dp[a]));

         for(j = ; j <= sum; ++j) {

             //1.不放第i块水晶;

             if(dp[a ^ ][j] > -)

                 dp[a][j] = dp[a ^ ][j];

             //2.放进去后，高塔变矮塔（第i块放在矮塔上了）;

             if(num[i] > j &&  dp[a ^ ][num[i] - j] > -)

                 dp[a][j] = max(dp[a][j], dp[a ^ ][num[i] - j] + j);

             //3.放进去后，高塔仍高（第i块放在矮塔上）;

             if(j + num[i] <= sum && dp[a ^ ][j + num[i]] > -)

                 dp[a][j] = max(dp[a][j], dp[a ^ ][j + num[i]]);

             //4.放进去后，高塔更高（第i块放在高塔上）.

             if(j >= num[i] && dp[a ^ ][j - num[i]] > -)

                 dp[a][j] = max(dp[a][j], dp[a ^ ][j - num[i]] + num[i]);

         }

     }

     if(dp[a][] > )

         cout << dp[a][] << endl;

     else

         cout << "Impossible" << endl;

 }