import java.util.Scanner;
import java.util.*;
public class Main {
public static void main
(String[] args
) { Scanner scanner
= new Scanner
(System.
in); int n = scanner.nextInt();
double s0 = scanner.nextDouble();
double s = scanner.nextDouble();
double [] A = new double[n];
double [] B = new double[n];
if(s0>=s)
else if(n==0)
else
{
for(int i=0; i<n; i++)
{
double a = scanner.nextDouble();
A[i]=a;
B[i]=A[i];
}
int ans=0;
for(int i=n-1; i>=1; i--)
{
if(B[i]>=10.1)
{
if((int)(B[i]-5.1)+s0>=s){
ans++;
}
else
{
ans++;
B[i-1]+=(int)(B[i]-5.1);
}
}
else
{
break;
}
}
if((B[0]>=10.1)&&((int)(B[0]-5.1)+s0>=s))
else
{
if(s0>=10.1)
{
A[n-1]+=(int)(s0-5.1);
s0-=(int)(s0-5.1);
s0-=0.1;
ans=1;
for(int i=n-1; i>=1; i--)
{
if(A[i]>=10.1)
{
if((int)(A[i]-5.1)+s0>=s){
ans++;
}
else
{
ans++;
A[i-1]+=(int)(A[i]-5.1);
}
}
else
{
break;
}
}
if((A[0]>=10.1)&&((int)(A[0]-5.1)+s0>=s))
else
}
else
}
}
}
}
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