C :: 3 Students Sharing Their Meals - Settle Bills Equally

There are 3 students (0=John, 1=Peter, 2=William) sharing their meals. Who does the cooking, does the shopping and pays for the bills. End of the month they sum it all up and settle the bills equally. Who must pay the most is outputted at the top, while the person that collects most is at the bottom. Students that have to pay the same amount are listed in the same order as they are ordered in the input. (receiving same amount, the same). Total of the settlement are rounded to whole cents. Sometimes they loose a cent, sometimes they gain one.

So I started making a plan what the program is supposed to do. Pen and paper:

1. Sum of the total amount from all the meals.
JohnPaid+PeterPaid+WilliamPaid=Total
Total / 3 = FairShare

calculate difference of all three the students

if JohnPaid == FairShare
print John receives 0.00

if JohnPaid > FairShare
print John receives difference

if JohnPaid < FairShare
print John pays difference

etc. (same for Peter and William)

Code:
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>

/* type definition of student */
typedef struct student {
int who; /* 0=John, 1=Peter, 2=William */
float paid; /* amount that student paid */

[Code] .....

Example in/outputs:

<0 39.85>
<1 30.83>
<2 35.43>
Peter pays 4.54
William receives 0.06
John receives 4.48

<1 106.32>
<0 88.14>
<2 88.14>
John pays 6.06
William pays 6.06
Peter receivers 12.12

Looking at this code, I see a lot of global (general) variables. Do I need to adjust this skeleton code I received or should I just add code?