#include <iostream>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <unordered_map>
#include <queue>
#include <string>
#include <math.h>
#include <cctype>
#include <cstdint>
#include <climits>
#include <iostream>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <unordered_map>
#include <queue>
#include <string>
#include <math.h>
#include <cctype>
#include <cstdint>
#include <climits>
#include <iomanip>
#define ll long long
#define endl "\n"
using namespace std;
map<pair<int,int>,int> dp;
int solve(int index,ll pos,vector<pair<int,int>>& nums,int target){
if(dp.find({index,pos}) != dp.end()) return dp[{index,pos}];
if(index == nums.size()) return pos == target? 0:-1;
int ret = -1;
for(int i = 0; i<= nums[index].second; i++){
int cur = solve(index +1,pos + nums[index].first * i,nums,target);
if(cur == -1) continue;
cur += i;
ret = max(cur,ret);
}
dp[{index,pos}] = ret;
return ret;
}
int main(){
ll m,l;
cin >> m >> l;
vector<pair<int,int>> pars;
for(int i = -m; i<= m; i++){
int a;
cin >> a;
pars.push_back({i,a});
}
int ans = solve(0,0,pars,l);
if(ans == -1) cout << "impossible" << endl;
else cout << ans << endl;
return 0;
}
