#include <cstdio>
double compute(double n) {
double left, right, mid;
if(n > 1) {
left = 1;
right = n;
} else {
left = 0;
right = 1;
}
while(right - left > 0.1) {
mid = (left + right) / 2;
if(mid * mid * mid > n) {
right = mid;
} else {
left = mid;
}
}
return mid;
}
int main() {
double n;
while(EOF != scanf("%lf", &n)) {
if(n < 0) {
n = -n;
printf("-");
}
printf("%.1lf\n", compute(n));
}
}