CODEFORCES problem 467/A George and Accommodation

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#include <iostream>
#include <cstdio>


using namespace std;

int main()
{
    int i, p, q, free, count=0;
    cin >> i;
    while(i--){
        cin >> p >> q;
        free = q-p;
        if(free>=2)
            count++;
    }
    cout << count << endl;

    return 0;
}