void max_min(int a[],int n,int *max,int *min,int *ave)
{
int i;
*max = *min = a[0];
for(i=1;i<n;i++){
if(a[i]>=*max)*max=a[i];
if(a[i]<=*min)*min=a[i];
*ave+=a[i]; }
*ave /= n;
}