#include <bits/stdc++.h> using namespace std; const int N = 310; int a[N], b[N]; bitset<N*N> dp; void ext(){ cout << "impossible\n"; exit(0); } int main(){ ios_base::sync_with_stdio(false); cin.tie(nullptr); int n, m, k; cin >> n >> m >> k; if(m < k) ext(); for(int i = 0; i < n; ++i){ cin >> a[i]; if(k > a[i]) ext(); } dp[0] = 1; for(int i = 0; i < m; ++i){ cin >> b[i]; dp |= (dp << b[i]); } int ans = 0; for(int i = 0; i < n; ++i){ for(int j = a[i]; j < N*N; ++j){ if(dp[j]){ ans += j; break; } } ans -= a[i]; } cout << ans << '\n'; }