#include <stdio.h>
#include <list>
#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <sstream>

using namespace std;

enum Direction {
    UP,
    DOWN,
    UNSET
}; 

int main(){
    string line;
    int safeReports = 0;
    stringstream wholeDoc;

    ifstream puzzle("input.txt", ifstream::in);

        while (getline(puzzle, line)) {
            istringstream lineStream(line);
            string numberString;
            list<int> currentLevels;
            while (getline(lineStream, numberString, ' ')) {
                int number = stoi(numberString);
                currentLevels.push_back(number);
            }

            int numOfLevelsInLine = currentLevels.size();
            int numOfLevelsProcessed = 0;
            auto curListIt = currentLevels.begin();
            curListIt++; //point to second item in list
            auto RevCurListIt = currentLevels.rbegin();
            RevCurListIt++; //points to second to last item
            enum Direction dir;
            bool dirSet =false;
            bool listDirty =false;
            

            //check first number, second number and last number to see if they all acend or deced
            //if not check second number, third number and last number to see if they accend or decend 
            //then check first number, second number and second to last to see if they accend or decend

            //set direction
            if ((currentLevels.front()>currentLevels.back())&&(*curListIt) > currentLevels.back()){
                dir = DOWN;
                dirSet=true;
            } else if((currentLevels.front()<currentLevels.back())&&((*curListIt)<currentLevels.back())){
                dir= UP;
                dirSet=true;
            }
            //check ends first. 
            if(!dirSet){
                int secondItem = (*curListIt);
                curListIt++; //points to thirdlist item from front
                int secondToLastItem = (*RevCurListIt); 
                RevCurListIt++;//points to 3rd to last item
                if((secondItem>(*curListIt)&&(secondItem>currentLevels.back()))){
                    dir=DOWN;
                    dirSet=true;
                    currentLevels.pop_front();//remove first item
                    listDirty=true;
                } else if((secondItem<(*curListIt)&&(secondItem<currentLevels.back()))){
                    dir = UP;
                    dirSet= true;
                    currentLevels.pop_front();
                    listDirty=true;
                } else if ((currentLevels.front()>currentLevels.back()&&(currentLevels.front()>secondToLastItem))){
                    dir = DOWN;
                    dirSet= true;
                }
                //check if the back item is the problem

            }

            //need to pull the first one to have something to compare to

            int prevlevel = currentLevels.front();
            currentLevels.pop_front();
            numOfLevelsProcessed++;
            if (prevlevel < currentLevels.front()){
                dir = DOWN;
            } else if (prevlevel > currentLevels.front()){
                dir = UP;
            } else {
                currentLevels.clear();
            }
            

            for (int level = currentLevels.front(); !currentLevels.empty();level=currentLevels.front()){
                if (abs(prevlevel-level)>3) {currentLevels.clear();break;}
                if(prevlevel==level){ currentLevels.clear();break;}
                if(dir==UP&&(prevlevel<currentLevels.front())) {currentLevels.clear();break;}
                if(dir==DOWN&&(prevlevel>currentLevels.front())) {currentLevels.clear();break;}
                
                prevlevel=currentLevels.front();
                currentLevels.pop_front();
                numOfLevelsProcessed++;

                if(numOfLevelsProcessed==numOfLevelsInLine){
                    safeReports++;
                }
            }
        }
cout << safeReports;
puzzle.close();
}