#include <stdio.h>
int main(void) {
int n,k;
int a[n],i=0,f=n-1;
for(i;i<n;i++)
{
}
long long int p=a[f];
while(1)
{
p*=a[f-=k];
if(a[f]-a[0]<=k)
break;
}
return 0;
}
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