#include <stdio.h>
#include <stdlib.h>
#define SIZE 50
typedef int bool;
#define true 1
#define false 0
int getMaxRange();
int getMileMarker();
void getMarkerPositions(int* markerPositions);
int getCurrentIndex(int* markerPositions, int startingMileMarker);
int getNumOfUnreachablePoints(int* markerPositions, int startingIndex, int maxRange);
int main() {
    int maxRange = getMaxRange();
    int startingMileMarker = getMileMarker();
    int markerPositions[SIZE];
    getMarkerPositions(markerPositions);

    int startingIndex = getCurrentIndex(markerPositions, startingMileMarker);
    int numOfUnreachablePoints = getNumOfUnreachablePoints(markerPositions, startingIndex, maxRange);

    printf("A total of %d points cannot be reached.", numOfUnreachablePoints);
}

int getNumOfUnreachablePoints(int* markerPositions, int startingIndex, int maxRange) {
    int numOfUnreachablePoints = -1;
    bool unreachable = false;
    int currentIndex;
    for (currentIndex = startingIndex; currentIndex < SIZE; currentIndex++) {
        if (markerPositions[currentIndex] == -1) break;
        int nextIndex = currentIndex + 1;
        if (abs(markerPositions[currentIndex] - markerPositions[nextIndex]) > maxRange)
            unreachable = true;
        if (unreachable) numOfUnreachablePoints++;
    }

    unreachable = false;
    for (currentIndex = startingIndex; currentIndex > 0; currentIndex--) {
        int nextIndex = currentIndex - 1;
        if (abs(markerPositions[currentIndex] - markerPositions[nextIndex]) > maxRange)
            unreachable = true;
        if (unreachable) numOfUnreachablePoints++;
    }
    return numOfUnreachablePoints;
}

int getCurrentIndex(int *markerPositions, int startingMileMarker) {
    int i = 0;
    int currentIndex = -1;
    while (i < SIZE && markerPositions[i] != -1) {
        if (markerPositions[i] == startingMileMarker) {
            currentIndex = i;
        }
        i++;
    }
    return currentIndex;
}

int getMaxRange() {
    int maxRange = -1;
    while (maxRange < 1) {
        printf("Enter maximum fuel range: ");
        scanf("%d", &maxRange);
        if (maxRange < 1)
            printf("Error! Positive values only!!\n");
    }
    return maxRange;
}

int getMileMarker() {
    int mileMarker = -1;
    while (mileMarker < 0) {
        printf("Enter starting mile marker location: ");
        scanf("%d", &mileMarker);
        if (mileMarker < 0)
            printf("Error! Non-negative values only!!\n");
    }
    return mileMarker;
}

void getMarkerPositions(int* markerPositions) {
    int count = 0;
    int currentNumber;
    printf("Enter mile marker positions:");
    do {
        scanf("%d", &currentNumber);
        markerPositions[count] = currentNumber;
        count++;

    } while(count <  SIZE && currentNumber != -1);
}