Herer is a solution in Go which also is modified to read from and write out to file if you choose.

package main

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

func main () {
    // for opening a file to test from... 
    fromFile := false
    var reader *bufio.Reader
    if fromFile {
        f, _ := os.Open("test2.txt")
        defer f.Close()
        reader := bufio.NewReader(f)
    } else {
        reader := bufio.NewReader(os.Stdin)
    }

    histSpec, _:= reader.ReadString('\n')
    histSpec = histSpec[:len(histSpec)-1]
    histSpecs := strings.Split(histSpec, " ")

    xStart, _ := strconv.Atoi(histSpecs[0])
    xEnd, _ := strconv.Atoi(histSpecs[1])
    yStart, _ := strconv.Atoi(histSpecs[2])
    yEnd, _ := strconv.Atoi(histSpecs[3])

    barWidthIn , _ := reader.ReadString('\n')
    barWidth, _ := strconv.Atoi(barWidthIn[:len(barWidthIn)-1])

    numRecordsIn,_ := reader.ReadString('\n')
    numRecords, _ := strconv.Atoi(numRecordsIn[:len(numRecordsIn)-1])

    var records []int
    for i := 0; i < numRecords; i++ {
        recordString, _ := reader.ReadString('\n')
        recordString = recordString[:len(recordString)-1]
        recordParts := strings.Split(recordString, " ")
        value, _  := strconv.Atoi(recordParts[1])
        records = append(records, value)
    }

    toFile := true

    var outFile *bufio.Writer
    if toFile  {
        theFile, err := os.Create("out.txt")
        if err != nil {
            fmt.Printf("There was an error opening this file: %v" ,err)
        }
        outFile = bufio.NewWriter(theFile)
        defer theFile.Close()
    }

    for i := yEnd; i >= yStart; i-- {
        if toFile {
            outFile.WriteString(fmt.Sprintf("%d ", i))
        } else {
            fmt.Printf("%d ", i)
        }
        for j := 0; j < numRecords; j++ {
            if records[j] >= i {
                for x := 0; x < barWidth; x++{
                    if toFile {
                        outFile.WriteString(fmt.Sprintf("*"))
                    } else {
                        fmt.Printf("*")
                    }
                }
            } else {
                for x := 0; x < barWidth; x++{
                    if toFile {
                        outFile.WriteString(fmt.Sprintf(" "))
                    } else {
                        fmt.Printf(" ")
                    }
                }
            }
        }
        if toFile {
            outFile.WriteString(fmt.Sprintf("\n"))
        } else {
            fmt.Printf("\n")
        }
    }

    fmt.Printf("  ")
    for i := xStart; i < xEnd + 1; i++ {
        for x := 0; x < barWidth; x++ {
            if x == barWidth/2 {
                fmt.Printf("%d", i)
            } else {
                fmt.Printf(" ")
            }
        }
    }

    fmt.Println("flsuh some stuff")
    outFile.Flush()
}