include <bits/stdc++.h>
using namespace std;
int main() {
int a, b, c, d, s; cin >> a >> b >> c >> d >> s; if (a + b == s) {
cout << '1';
} else if (a + c == s) {
cout << '1';
} else if (a + d == s) {
cout << '1';
} else if (b + c == s) {
cout << '1';
} else if (b + d == s) {
cout << '1';
} else if (c + d == s) {
cout << '1';
} else {
cout << "-1";
}
return 0;
}
