#include<bits/stdc++.h> 
#define ll long long 
#define LL __int128_t 
#define PB push_back
#define MK make_pair
#define fi first
#define se second
#define FOR(i, x, y) for (decay<decltype(y)>::type i = (x), _##i = (y); i <= _##i; ++i)
#define FORD(i, x, y) for (decay<decltype(x)>::type i = (x), _##i = (y); i >= _##i; --i)
#define debug(x) cout<< "\033 -> "<<#x<<": "<<x<<endl
using namespace std;
string s;
void dfs(int p, int *num)
{	
	if(p == (s.size()+1)/2+1)
	{
		int up = s.size()/2, flag = 1;
		for(int i = 1; i <= up; ++i)
		{
			int X = 0;
			for(int j = 1; j <= i; ++j)
				X = (X+num[p-j]*num[p-i+j-1])%10;
			if(X != s[s.size()-i]-'0') { flag = 0; break;}
		}

		if(flag) { for(int i = 1; i < p; ++i) { cout<<num[i]; } exit(0); }
		return;
	}
	for(int i = 0; i <= 9; ++i)
	{
		num[p] = i;
		int X = 0;
		for(int j = 1; j <= p; ++j)
			X = (X+num[j]*num[p-j+1])%10;
		if(X == s[p-1]-'0') dfs(p+1, num);
	}
}
int main() 
{ 
	//freopen("1.in","r",stdin); 
	ios::sync_with_stdio(false); 
	cin.tie(NULL);
	cin >> s;
	if(s.size()%2 == 0) {cout<<-1<<endl; return 0;}
	int num[26];
	dfs(1, num);
	cout<<-1<<endl;
	return 0; 
}