Persian Party

#include <iostream>
using namespace std;
int main(){

    int n;
        cin>> n;

    int a[n], d[n], v=0;

        for(int i=0; i<n; i++){
            cin>> a[i];
            cin>> d[i];

            v+=d[i]-a[i]+1;
        }
    cout<< v;
}