Inviting Customer Count

Inviting Customer Count: A company plans a viral marketing strategy in which an existing customer will invite N other new customers every day for D days. At the end of the Dth day, a customer will get a gift and must leave (the left customers will not invite any new customers on D+1 th day). A customer who has got a gift and left will not be invited again. On Day 1 there will be only one customer to begin with and this customer will leave at the end of the Dth day. Given N and D, the program must calculate the number of customers who are eligible to invite new customers on the Tth day.

Input Format:
The first line will contain N and D separated by a space.
The second line will contain T.

Output Format:
The first line will contain the number of customers who are eligible to invite new customers on the Tth day

Boundary Conditions:
1 <= N <= 5
1 <= D <= 10
1 <= T <= 50

Example Input/Output 1:
Input:
2 6
3

Output:
9

Example Input/Output 2:
Input:
2 6
7

Output:
726

Explanation:
Customers remaining at the end of day 1 is = 3
Customers remaining at the end of day 2 is = 9
Customers remaining at the end of day 3 is = 27
Customers remaining at the end of day 4 is = 81
Customers remaining at the end of day 5 is = 243
Customers remaining at the end of day 6 is = 726 (3 leave)
So customers who can invite on 7th day = 726

#include<stdio.h>
#include <stdlib.h>
int main(){
    int n,d,t,c=0,x=1,h=1,f=1,a[1000];
    scanf("%d %d",&n,&d);
    scanf("%d",&t);
    a[0]=0;
    for(int i=1;i<t;i++){
        a[x]=f*n;
        if(x==1) a[1]++;
        f=f+(f*n);
        c++;
        if(c>=d){
            f=f-a[h];
            h++;
        }
        x++;
    }
printf("%d",f);
}