#include <stdio.h>
#include<math.h>
void bu(int arr[], int sz) {
int i = 0;
for (i = 0; i < sz - 1; i++) {
int j = 0, flag = 0;
for (j = 0; j < sz - 1 - i; j++) {
if (arr[j] < arr[j + 1]) {
int tmp = arr[j];
arr[j] = arr[j + 1];
arr[j + 1] = tmp;
flag = 1;
}
}
if (flag == 0)
break;
}
}
int main() {
int arr[1000], n;
scanf("%d", &n);
int i = 0;
for (i = 0; i < n; i++) {
scanf("%d", &arr[i]);
}
bu(arr, n);
for (i = 0; i < n; i++) {
int tmp = sqrt(arr[i]);
if (sqrt(arr[i]) - tmp != 0) {
printf("%d", arr[i]);
break;
}
}
return 0;
}