Array: Find the second height value from a given array in C

Second Height Value from a Given Array 

#include<stdio.h>
int main()
{
    int i,n;
    int a[100];
    printf("Enter the size of array: \n");
    scanf("%d",&n);
    for(i=0;i<n;i++)
    {
        printf("Enter the %d value of array: \n",i+1);
        scanf("%d",&a[i]);
    }
    int max=a[0];
    int j=0;
    for(i=0;i<n;i++)
    {
        while(a[i]>max)
        {
            max=a[i];
            j=i;
        }
    }
    int semax=a[n-j-1];
    for(i=0;i<n;i++)
    {
        while(semax<a[i]&&j!=i)
            semax=a[i];
    }

    printf("Max value of array is:%d\n",max);
    printf("2nd Max value of array is:%d\n",semax);
}