/*
 * Slow: O(2^strlen)
 */
#include <bits/stdc++.h>
using namespace std;
#define PB push_back
#define ZERO (1e-10)
#define INF int(1e9+1)
#define CL(A,I) (memset(A,I,sizeof(A)))
#define DEB printf("DEB!\n");
#define D(X) cout<<"  "<<#X": "<<X<<endl;
#define EQ(A,B) (A+ZERO>B&&A-ZERO<B)
typedef long long ll;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef pair<int,int> ii;
typedef vector<ii> vii;
#define IN(n) int n;scanf("%d",&n);
#define FOR(i, m, n) for (int i(m); i < n; i++)
#define F(n) FOR(i,0,n)
#define FF(n) FOR(j,0,n)
#define FT(m, n) FOR(k, m, n)
#define aa first
#define bb second
void ga(int N,int *A){F(N)scanf("%d",A+i);}
unordered_map<ll,int> dp;
char s[66666];
ll N,L;
int dyn(ll b){
    if(b==(1LL<<L)-1)return 0;
    if(dp.count(b))return dp[b];
    int v=INF;
    F(L)if(b!=(b|b>>i))v=min(v,dyn(b|b>>i)+1);
    return dp[b]=v;
}
int main(void){
    scanf("%s",s),L=strlen(s);
    F(L)N<<=1,N|=s[i]-48;
    if(*s^49)return puts("-1"),0;
    printf("%d\n",dyn(N));
    return 0;
}