#include <bits/stdc++.h>
using namespace std;
#define int long long
#define fi first
#define se second
typedef pair<int,int> pii;
const int N = 305, M = 305;
int dp[M][90005], a[N], b[M];
signed main(){
ios::sync_with_stdio(0); cin.tie(0);
int n,m,k; cin>>n>>m>>k;
int tot = 0;
for(int i=1; i<=n; i++) cin>>a[i], tot+=a[i];
for(int i=1; i<=m; i++) cin>>b[i];
dp[0][0] = 1;
for(int i=1; i<=m; i++){
for(int j=0; j<90005; j++){
if(dp[i-1][j]) dp[i][j] = 1;
else if(j-b[i] >= 0) dp[i][j] = dp[i-1][j-b[i]];
}
}
int ans = -1;
for(int i=tot; i<=90005; i++){
if(dp[m][i]) {ans = i-tot; break;}
}
if(ans == -1) cout<<"Impossible";
else cout<<ans;
return 0;
}
