trapezoidal rule using c program

#include<stdio.h>
#include<conio.h>
void main()
{
int i,j,n;
float arr[10],sum,integral,h;

printf("Enter the interval: ");
scanf("%f",&h);
printf("Enter Number of terms: ");
scanf("%d",&n);
printf("Enter the values of y:- \n");
for(i=0;i<n;i++)
{
scanf("%f",&arr[i]);
}
sum=(arr[0]+arr[n-1])/2;
for(j=1;j<=n-2;j++)
{
sum=sum+arr[j];
}
integral=h*sum;
printf("Output= %f",integral);
getch();
}


Enter the interval: 1
Enter Number of terms: 7
Enter the values of y:-
81
16
1
0
1
16
81
Output= 115.000000