CodeForces 233B. Non-square Equation【状压】

B. Non-square Equation

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

Let's consider equation:

x2 + s(x)·x - n = 0, 

where x, n are positive integers, s(x) is the function, equal to the sum of digits of number x in the decimal number system.

You are given an integer n, find the smallest positive integer root of equation x, or else determine that there are no such roots.

Input

A single line contains integer n (1 ≤ n ≤ 1018) — the equation parameter.

Please, do not use the %lld specifier to read or write 64-bit integers in С++. It is preferred to use cin, cout streams or the %I64d specifier.

Output

Print -1, if the equation doesn't have integer positive roots. Otherwise print such smallest integerx (x > 0), that the equation given in the statement holds.

Examples

input

2

output

1

input

110

output

10

input

4

output

-1

Note

In the first test case x = 1 is the minimum root. As s(1) = 1 and 12 + 1·1 - 2 = 0.

In the second test case x = 10 is the minimum root. As s(10) = 1 + 0 = 1 and102 + 1·10 - 110 = 0.

In the third test case the equation has no roots.

AC代码：

#include<cstdio>#include<cmath>typedef __int64 LL;bool Judge(LL x,LL s) {LL sum=0;while(x) {sum=sum+x%10; x/=10;} return sum==s; }int main(){LL N;while(~scanf("%I64d",&N)) {        LL n=17*9,ans=-1;for(int i=1;i<=n;++i) {    LL t=i*i+4*N;LL tem=sqrt(t);if(tem*tem==t)  if( (tem-i)%2==0) { LL x=(tem-i)>>1;    if(Judge(x,i)) {    ans=x; break;}}} printf("%I64d\n",ans); }return 0; }