FCFS algorithm C++ program please help!

[naomisan]

Hi to all,
im just a newbie here..
can someone help me with my program about FCFS scheduling algo,
here the code that i made..
the first 2 process is correct but the succeding process is not.. please help me with the right computation.

note: TAT= Time of completion - Arrival Time;
[code=c]
#include<stdio. h>
#include<conio. h>

int proc,x,at[10],bt[10],sum;
main()
{
clrscr();

printf ("Input number of process: ");
scanf("%d",&pro c);

printf ("\n\nProcess#\ t\tArrival Time\t\tBurst Time\tTat");

for (x=1;x<=proc;x+ +)
{
gotoxy (4,4+x);
printf("%d",x);


gotoxy (30,4+x);
scanf ("%d", &at[x]);

gotoxy (55,4+x);
scanf("%d",&bt[x]);

sum=sum+1+bt[x]-at[x];

gotoxy (65,4+x);
printf("%d",sum );
}
getch();

return 0;
}
[/code]
Thanks a lot!

[Ariharan]

Read Arrival Time and Burst Time for all Process
Let WaitingTime[0] = 0 and TAT[0]=BurstTime[0]
WaitingTime[i]=TAT[i-1]-ArrivalTime[i]
TAT[i]=BurstTime[i]+WaitingTime[i]