C program to evaluate responses to a multiple-choice test

 
#include<stdio.h>
#include<conio.h>

#define STUDENTS 3
#define ITEMS 25

void main()
{
    char key[ITEMS+1], response[ITEMS+1];
    int count, i, student, n, correct[ITEMS+1];

    printf("Input key to the items");

    for(i=0;i<ITEMS;i++)
    {
        scanf("%c", &key[i]);
        scanf("%c", &key[i]);
    }

    key[i]='';

    for(student=1; student<=STUDENTS; student++)
    {
        count=0;
        printf("n");
        printf("Input responses of student - %d",student);

        for(i=0;i<ITEMS;i++)
        {
            scanf("%c", &response[i]);
        }

        response[i]='';

        for(i=0;i<ITEMS;i++)
        {
            correct[i]=0;
        }

        for(i=0;i<ITEMS;i++)
        {
            if(response[i] == key[i])
            {
                count=count+1;
                count[i]=1;
            }
        }

        printf("n");
        printf("student-%d",student);
        printf("score is %d out of %d",count,ITEMS);
        printf("Response to the items below are wrong");

        n=0;

        for(i=0;i<ITEMS;i++)
            if(correct[i]==0)
            {
                printf("%d",i+1);
                n=n+1;
            }

        if(n==0)
            printf("NIL");
        printf("n");

    }
}

 
Input key to the items
abcdabcdabcdabcdabcdabcda

Input responses of student-1
abcdabcdabcdabcdabcdabcda

student-1
score is 25 out of 25
response to the following items are wrong
NIL

Input responses of student-2
abcddcbaabcdabcdddddddddd

student-2
score is 14 out of 25
Response to the following items are wrong
5 6 7 8 17 18 19 21 22 23 25

Input responses of student-3
aaaaaaaaaaaaaaaaaaaaaaaaa

student-3
score is 7 out of 25
Response to the following items are wrong
2 3 4 6 7 8 10 11 12 14 15 16 18 19 20 22 23 24