#include<iostream>
using namespace std;
int main()
{
   int cost;//花费
   int month;//月份
   int add = 0;//存在妈妈手里的钱
   int own = 0;//自己起始手里的钱
   int failmonth;//失败月份
   bool flag = true;//设置旗帜
   for (int i = 1; i <= 12; i++)
   {
   	cin >> cost;
   	own += 300 - cost;
   	add += own / 100 % 10 * 100;
   	own = own % 100;
   	if (own < 0)
   	{
   		flag = false;
   		month = -i;
   		continue;
   	}

   }
   if (flag)
   {
   	cout << (add + own) + add * 0.2 << endl;
   }
   else
   {

   	cout << month << endl;
   }


   return 0;


}