I have 16 euros in my pocket and I play head or tails with `p = 1/2`

. Every time I bet on heads. If the coin flip is head then I earn 0 and if is tails I lose 1 euro. What is the probability of hitting 18 times (consecutive or not) heads and to be left 3 euros in my pocket.

I tried to simulate this problem in R:

```
squid_bridge = function(a,n,p) {
players = a
while (position > 0 & position < n) {
jump = sample(c(0,1),1,prob=c(1-p,p))
position = position + jump
}
if (position == 0)
return(1)
else
return(0)
}
n = 18
trials = 100000
a = 16
p = 1/2
set.seed(1)
simlist = replicate(trials, squid_bridge(a, n, p))
```

But it does seem to work.Any help?