Submission #3046283

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;

int main() {
    string s;
    cin >> s;
    bool used[s.length()] = {};
    int times = 0;
    while (1) {
        char before = '5';
        int before_pos;
        bool update = false;
        for (int i = 0; i < s.length(); ++i) {
            if (before == '5' && s[i] == '2' && !used[i]) {
                before = '2';
                before_pos = i;
            } else if (before == '2' && s[i] == '5' && !used[i]) {
                before = '5';
                used[before_pos] = true;
                used[i] = true;
                update = true;
            }
        }
        if (!update) break;
        times++;
    }
    bool possible = true;
    for (int i = 0; i < sizeof (used); ++i) if (!used[i]) possible = false;
    cout << (possible ? times : -1) << endl;
    return 0;
}

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