#!/usr/bin/env tclsh9.0

proc issafe {report} {
    set decrease 0; set increase 0
    set curr [lindex $report 0]
    foreach value [lrange $report 1 end] {
        if {$value > $curr} {set increase 1}
        if {$value < $curr} {set decrease 1}
        set dist [expr {abs($value - $curr)}]
        if {$dist < 1 || $dist > 3} {
            return 0
        }
        set curr $value
    }
    if {$increase && $decrease} {return 0}
    return 1
}

proc check {report} {
    if {[issafe $report]} {return 1}
    for {set i 0} {$i < [llength $report]} {incr i} {
        if {[issafe [lreplace $report $i $i]]} {return 1}
    }
    return 0
}

set count 0
while {[gets stdin line] >= 0} {
    if {$line eq ""} continue
    set report [split $line " "]
    if {[check $report]} {incr count}
}
puts $count