package main

import (
    "fmt"
    "os"
    "strings"
    "strconv"
)

func check(e error) {
    if e != nil {
        panic(e)
    }
}

func main() {
    // read in file as lines
    dat, err := os.ReadFile("data.txt")
    check(err)
    lines := strings.Split(string(dat), "\n")

    // valid reports
    valid := 0

    for i := range len(lines) - 1 {
        str_levels := strings.Split(lines[i], " ")
        
        // convert to integer
        levels := make([]int, len(str_levels))
        for j := range str_levels {
            levels[j], err = strconv.Atoi(str_levels[j])
            check(err)
        }

        // check for validity
        if levels[0] > levels[1] {
            // decreasing sequence
            valid += 1
            for j := range len(levels) - 1 {
                if levels[j] - levels[j+1] <= 0 || levels[j] - levels[j+1] > 3 {
                    valid -= 1
                    break
                }
            }
        } else if levels[0] < levels[1] {
            // increasing sequence
            valid += 1
            for j := range len(levels) - 1 {
                if levels[j+1] - levels[j] <= 0 || levels[j+1] - levels[j] > 3 {
                    valid -= 1
                    break
                }
            }
        }
    }

    fmt.Println(valid)
}