#include <iostream>
using namespace std;

void p(long long l){
    string s = "";
    while(l > 0){
        s = ((char)(l % 2 + '0')) + s;
        l /= 2;
    }
    cout << s << endl;
}

int main(){
    ios_base::sync_with_stdio(false);
    string s;

    cin >> s;

    if(s[0] == '0'){
        cout << -1 << endl;
        return 0;
    }

    long long S1 = 0;

    for(int i = 0; i < s.length(); i++){
        S1 *= 2;
        S1 += s[i] - '0';
    }

    long long A;
    int min = 100000;

    long long G = ((long long)1 << s.length()) - 1;
    if(G == S1){
        min = 0;
    }

    //cout << S1 << " " << G << endl;

    for(int i1 = 1; i1 <= 39 && min > 1; i1++){
        A = S1;
        A = A | (A >> i1);
        if(A == G) min = 1;
        long long S2 = A;
        //p(A);

        for(int i2 = 1; i2 <= 39 && min > 2; i2++){
            A = S2;
            A = A | (A >> i2);
            if(A == G) min = 2;
            long long S3 = A;
            //cout << '\t';
            //p(A);

            for(int i3 = 1; i3 <= 39 && min > 3; i3++){
                A = S3;
                A = A | (A >> i3);
                if(A == G) min = 3;
                long long S4 = A;

                //cout << '\t\t';
                //p(A);

                for(int i4 = 1; i4 <= 39 && min > 4; i4++){
                    A = S4;
                    A = A | (A >> i4);
                    if(A == G) min = 4;
                    long long S5 = A;

                    for(int i5 = 1; i5 <= 39 && min > 5; i5++){
                        A = S5;
                        A = A | (A >> i5);
                        if(A == G) min = 5;
                        /*long long S6 = A;

                        for(int i6 = 1; i6 <= 39 && min > 6; i6++){
                            A = S6;
                            A = A | (A >> i6);
                            if(A == G) min = 6;
                        }*/
                    }
                }
            }
        }
    }

    if(min == 100000) cout << 6 << endl;
    else cout << min << endl;

    return 0;
}

// 1000000000000000000000000000000000000000