#include <stdio.h>
#include <stdlib.h>
#include <string.h>

char tmp[100];


char *readRow(FILE *f){
  int i,j;

  j = 0;
  for(i = 0; i < 99; ++i)
    tmp[i] = 0;

  while((i = fgetc(f)) != '\n')
    tmp[j++] = i;
  
  return tmp;
}

int *readEntry(FILE *f){
  int i,j;

  j = 0;
  for(i = 0; i < 99; ++i)
    tmp[i] = 0;

  while(((i = fgetc(f)) != '\n') &&
	i != ' ')
    tmp[j++] = i;
  
  return atoi(tmp);
}

int readInt(FILE *f){
  return atoi(readRow(f));
}

int min_abs(int a, int b){
  if(b > 0)
    return 0;
  a = abs(a);
  b = abs(b);

  if(a < b)
    return a;
  else
    return b;
}

void calculateWork(int *w, int p){
  int i,j,k,l;
  long long work = 0;

  for(i = 0; i < p; ++i)
    if(w[i] > 0){
      l = 1;
      while(w[i]){
	if((i-l) >= 0)
	  j = min_abs(w[i], w[i-l]);
	else
	  j = 0;
	if((i+l) <= p)
	  k = min_abs(w[i], w[i+l]);
	else
	  k = 0;


	w[i] = w[i] - j;
	w[i-l] += j;
	work += l * j;
	
	if((w[i] - k) < 0)
	  k = w[i];
	
	w[i] -= k;
	w[i+l] += k;
	work += l * k;
	++l;
      }
    }

  printf("%lli\n", work);
}

int main(int argc, char **argv){
  int *w;
  FILE *f;
  int p,i;
  p = 1;

  f = fopen("gergovia.in", "r");


  while(p != 0){
    p = readInt(f);
    w = (int*) malloc(sizeof(int) * p);
    for(i = 0; i < p; i++){
      w[i] = readEntry(f);
    }
    if(p != 0)
      calculateWork(w,p);
  }

  return 0;
  
  
  
}