#include <bits/stdc++.h>
using namespace std;
#define int long long
typedef pair<int,int> pii;
#define fi first
#define se second
#define debug(x) cerr<<#x<<" is "<<x<<endl;
int dp[305][100005];//dp chefs sum = POSSIBLE
signed main(){
int n,m,k;cin>>n>>m>>k;
int a[n],b[m+1];
int s=0;
for(int i=0;i<n;i++){
cin>>a[i];
s+=a[i];
}
sort(a,a+n);
for(int i=1;i<=m;i++){
cin>>b[i];
}
//int ans=LLONG_MAX;
dp[0][0]=1;
for(int i=1;i<=m;i++){
for(int j=0;j<100005;j++){
if(j-b[i]<0)dp[i][j]=dp[i-1][j];
else dp[i][j]=max(dp[i-1][j],dp[i-1][j-b[i]]);
}
}
//debug(dp[1][1])debug(dp[2][3])debug(dp[2][1])
for(int i=s;i<100005;i++){
if(dp[m][i]!=0){
cout<<i-s<<'\n';
return 0;
}
}
cout<<"Impossible\n";
}
