#include <iostream>
#include <fstream>

using namespace std;

ifstream fin("medii.txt");


int contor=0;

int cifra(float x, int &y){
    y = ((int)x)%10;
}


int main()
{
    int y;
    cifra(123.45, y);

    double a, b;
    while(fin >> a >> b)
    {
        int y1,y2;
        cifra(a,y1);
        cifra(b,y2);
        if (y1+1==y2) contor++;
    }

    cout << contor << endl;
    return 0;
}