#include<iostream.h>
#include<conio.h>
#include<math.h>
int main()
{
int a[20];
double sd=0,c,b,average=0,n=1,i=0,karesd=0,sum=0;

do
{
cout<<"enter a number"<<endl;
cin>>a[i];

c=i;
b=i;
i++;
}
while(a[i]!=0)
for(i=0;i<=c;i++)
{
sum=sum+a[i];
average=sum/i;
}
for(i=0;i<=b;i++)
karesd=karesd+((pow(a[i]-average),2)/i);
sd=sqrt(karesd);
cout<<"standard deviation = "<<sd;

getch();

return 0;

}