You have

for (vertline = 1; vertline < 20; vertline += 0.2F)

So vertline*5 will give you integers ranging from 5 - 99

If 5 is the first, then 8 and 11 are the 4th and 7th 8%7 == 1 and 11%7 == 4

So you could do

for (vertline = 1; vertline < 20; vertline += 0.2F)

So vertline*5 will give you integers ranging from 5 - 99

If 5 is the first, then 8 and 11 are the 4th and 7th 8%7 == 1 and 11%7 == 4

So you could do

```
for (vertline = 1; vertline < 20; vertline += 0.2F)
{
int line = vertline*5
if(line%7 == 1 || line%7 == 4)
// Do nothing
else
{
//Draw line
}
}
```