find mean with sd

#include<stdio.h>

main()
{
float arr[10];
float sum=0;
float mean=0;
float std1=0;
float std2;
int i,j,k;
for(i=0;i<10;i++)
{
printf("Enter number %d>>",i+1);
scanf("%f",&arr[i]);
sum+=arr[i];

}
mean=sum/i;
for(i=0;i<10;i++)
{
std1=std1+((arr[i]-mean)*(arr[i]-mean));

}
std2=std1/i;

printf("Mean = %f\nstanderd diviation = %f",mean,std2);
}