{
p = ($2 -$1) < 0 ? -1 : 1
safe = 1
for (i=2;i<=NF;i++) {
d = ($i - $(i-1))
q = d < 0 ? -1 : 1
if (p != q || d>3 || d<-3 || d == 0) {
safe = 0
break
}
#print NR, $0 , p, safe
S += safe
END {
print S