I'm starting to learn programming in C, and I have this task where I have to write a program with part of the code on another file. But I'm having problems with that last part because I'm using matrices. 

Here's the main body:

```
#include <stdio.h>
#include "otsenkatry.c"

int main()
{
    int i, j;
    int a[i];
    int s, gru;
    char A, B, C, D, E;

    printf("Introduce the number os students ", &s);
    fflush(stdout);
    scanf("%d", &s);
    printf("Introduce their grades\n");
    fflush(stdout);

    for (i = 0; i<s; i++)
    { 
        printf("a[%d] = ", i); 
        fflush(stdout);
        scanf("%d", &a[i]);

        printf("Grade: %d  %d \n", a, otsenkatry(a));
        fflush(stdout);//}
    }

    return 0;                       
}

```

And that's the part with the problem:

```
int otsenkatry (int* a)
{
    int i;
    int gru;

    if (a[i]<51)
    {   
        gru=2;
    }
    if (a[i]>50 && a[i]<69)
    {
        gru=3;
    }
    if (a[i]>69 && a[i]<=85)
    {
        gru=4;
    }
    if (a[i]>85 && a[i]<=100)
    {
        gru=5;
    }

    return gru;                         
}

```

I figured, that it has to do with the pointers, but I don't know how to alter it.