#include<cstdio>
#include<iostream>
#include<cstring>
#include<cmath>
#include <bits/stdc++.h>
using namespace std;
const int maxn = 200005;
const int maxm = 800005;
int h[maxm], num[maxn];
int n, m;
int lowbit(int x)
{
return x & (-x);
}
void update(int x)
{
while (x <= n)
{
h[x] = num[x];
for (int i = 1; i < lowbit(x); i <<= 1)
{
h[x] = max(h[x], h[x - i]);
}
x += lowbit(x);
}
return ;
}
int findans(int begin, int end)
{
int ans = 0;
while (end >= begin)
{
ans = max(ans, num[end]);
end--;
for (; end - lowbit(end) >= begin; end -= lowbit(end))
{
ans = max(ans, h[end]);
}
}
return ans;
}
int main()
{
n=200005;
int ans = -1;
int teshu = 0;
int now;
memset(h, 0, sizeof(h));
while (scanf("%d", &now) != EOF)
{
if (now < 0)
{
continue;
}
if (now >= 10000)
{
now %= 10000;
if (now == 0)
{
teshu += 5;
}
else
{
int cur = max(findans(1, now), teshu) + 5;
ans = max(ans, cur);
num[now] = cur;
update(now);
}
}
else
{
if (now == 0)
{
teshu += 5;
}
else
{
int cur = max(findans(1, now), teshu) + 1;
ans = max(ans, cur);
num[now] = cur;
update(now);
}
}
}
cout<<ans<<endl;
return 0;
}