#include <fstream>
#include <iostream>
using namespace std;
bool inceput[105], sfarsit[105];
/*un element din vectorii inceput si sfarsit are valoarea de adevar daca incepe sau se termina la pozitia respectiva un interval */
int main(){
int n;
ifstream fin("titu.in");
fin >> n;
int a,b;
for(int i = 0; i < n; i++){//O(n)
fin >> a >> b;
inceput[a] = true;
sfarsit[b] = true;
}
fin.close();
int d = 0, k = 0;
for(int i = 0; i < 105; i++){//O(1)
if(inceput[i])
d++;
if(sfarsit[i]){
if((--d)==0)k++;
}
}
cout << k;
}
