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;

}