#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
const int N = 1e6 + 10;
int t, n, m, k, l, r, op, y;
ll x;
string str;
void solve() {
    getline(cin, str);
    str.push_back('x');
    x = -1;
    for (char&ch : str) {
        if (isdigit(ch)) {
            if(x==-1)x=0;
            x = x * 10 + (ch - '0');
        } else if (x!=-1 && isalpha(ch)) {
            if (x > INT_MAX) {
                cout << -1;
            } else {
                cout << x;
            }
            return ;
        }
    }
    cout << -1;
}
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    solve();
    return 0;
}