to extract and display the maximum prime digit from a number

class maxprimedigit
{
public void compute(int c)
{
int b;
int n,big=0,d,count=0,i;

do{
n=c%10;
for(i=1;i<=n;i++)
{
if(n%i==0)
count=count+1;}
if(count==2)
{ if(big big=n;
count=0;
}
count=0;
c=c/10;
}

while(c!=0);
System.out.println(big+"is the maximum prime digit number");
}
}