#include <stdio.h>
#include <math.h>

int main( int argc, char ** argv )
{
    unsigned long number[256*1024];
    int counter = 0;
    while( scanf("%lu",&number[counter]) != EOF )
    {
        counter++;
    }

    for( counter--; counter >= 0; counter-- )
        printf("%.4f\n",sqrt(number[counter]));
    return 0;
}

It isn't ok
http://ideone.com/aoWHQT