#include <iostream>
#include <sstream>
#include <iomanip>
#include <vector>
#include <string>
#include <map>
#include <set>
#include <algorithm>
#include <numeric>
#include <iterator>
#include <functional>
#include <complex>
#include <queue>
#include <stack>
#include <cmath>
#include <cassert>
#include <cstring>
using namespace std;
typedef long long LL;
typedef complex<double> CMP;

class LotteryCheating { public:
	int minimalChange(string ID) 
	{
		int minMod = ID.size();

		for(LL x=0;; ++x)
		{
			string s;
			{stringstream ss; ss << x*x; ss >> s;}

			if( s.size() > ID.size() )
				break;
			s = string(ID.size()-s.size(),'0')+s;
			int c = 0;
			for(int i=0; i<ID.size(); ++i)
				if( s[i] != ID[i] )
					++c;
			minMod = min(minMod, c);
		}

		return minMod;
	}
};

// BEGIN CUT HERE
#include <ctime>
double start_time; string timer()
 { ostringstream os; os << " (" << int((clock()-start_time)/CLOCKS_PER_SEC*1000) << " msec)"; return os.str(); }
template<typename T> ostream& operator<<(ostream& os, const vector<T>& v)
 { os << "{ ";
   for(typename vector<T>::const_iterator it=v.begin(); it!=v.end(); ++it)
   os << '\"' << *it << '\"' << (it+1==v.end() ? "" : ", "); os << " }"; return os; }
void verify_case(const int& Expected, const int& Received) {
 bool ok = (Expected == Received);
 if(ok) cerr << "PASSED" << timer() << endl;  else { cerr << "FAILED" << timer() << endl;
 cerr << "\to: \"" << Expected << '\"' << endl << "\tx: \"" << Received << '\"' << endl; } }
#define CASE(N) {cerr << "Test Case #" << N << "..." << flush; start_time=clock();
#define END	 verify_case(_, LotteryCheating().minimalChange(ID));}
int main(){

CASE(0)
	string ID = "1"; 
	int _ = 0; 
END
CASE(1)
	string ID = "1234"; 
	int _ = 2; 
END
CASE(2)
	string ID = "9000000000"; 
	int _ = 1; 
END
CASE(3)
	string ID = "4294967296"; 
	int _ = 0; 
END
CASE(4)
	string ID = "7654321"; 
	int _ = 3; 
END
CASE(5)
	string ID = "2"; 
	int _ = 1; 
END
CASE(6)
	string ID = "4"; 
	int _ = 0; 
END
CASE(7)
	string ID = "8"; 
	int _ = 1; 
END
CASE(8)
	string ID = "1111111111"; 
	int _ = -1; 
END
CASE(9)
	string ID = "00201"; 
	int _ = 1; 
END

}
// END CUT HERE
