output_description: Print the number of people sitting at the theater.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N
      l_1 r_1
      :
      l_N r_N
attempt: #include <bits/stdc++.h>
  using namespace std;
  #define REP(i, n) for(int i = 0;i < n;i++)
  #define REPR(i, n) for(int i = n;i >= 0;i--)
  #define FOR(i, m, n) for(int i = m;i < n;i++)
  typedef int64_t llong;
  char moji[26]={'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
  char moji2[26]={'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};
  char moji3[10]={'0','1','2','3','4','5','6','7','8','9'};
  #define Sort(a) sort(a.begin(),a.end());
  #define Reverse(a) reverse(a.begin(),a.end());
  #define ld PRId64
  
  int main(){
      int n;
      cin >> n;
      llong ans=0;
      int l,r;
      REP(i,n){
          cin >> l >> r;
          ans+=r-l+1;
      }
      cout << ans << endl;
  
  }
problem_description: Statement
  
  Joisino is working as a receptionist at a theater.
  
  The theater has 100000 seats, numbered from 1 to 100000.
  
  According to her memo, N groups of audiences have come so far, and the i-th
  group occupies the consecutive seats from Seat l_i to Seat r_i (inclusive).
  
  How many people are sitting at the theater now?
samples: [{"input": "1\n    24 30", "output": "7\n    \n\nThere are 7 people, sitting at Seat 24,25,26,27,28,29 and 30.\n\n* * *"}, {"input": "2\n    6 8\n    3 3", "output": "4"}]