using System;
using System.Linq;
using System.Collections.Generic;

namespace Contest
{
  class Program
  {
    static void Main(string[] args)
    {
      ABC072.B();
    }
    class ABC072
    {
      public static void A()
      {
        var N = Read.Str();
        Console.WriteLine(N.Contains('9') ? "Yes" : "No");
      }
      public static void B()
      {
        var N = Read.Int();
        var LR = Read.TupleInt(N);
        int sum = 0;
        foreach(var lr in LR)
        {
          sum += lr.Item2 - lr.Item1 + 1;
        }
        Console.WriteLine(sum);
      }
      public static void C()
      {
        var N = Read.Int();
        var A = Enumerable.Range(0, N).Select(i => Read.Int()).ToArray();
        var freq = Util.Frequency(A);
        Console.WriteLine(freq.Values.Count(x => x % 2 == 1));
      }
      public static void D()
      {
        var N = Read.Int();
        var M = Read.Int();
        var Rs = Read.Int();
        var R = Read.IntN();
        var Adj = Read.AdjacencyListWithWeight(N, M);
        var dist = Util.DistFromAdj(N, Adj);
        Util.WarshallFloyd(dist);
        var dist2 = new long[Rs, Rs];
        for(int i = 0; i < Rs; ++i)
        {
          for(int j = 0; j < Rs; ++j)
          {
            dist2[i, j] = i == j ? 0 : dist[R[i] - 1, R[j] - 1];
          }
        }
        var dp = new long[Rs, 1 << Rs];
        for (int i = 0; i < Rs; ++i)
        {
          for (int j = 0; j < (1 << Rs) - 1; ++j)
          {
            dp[i, j] = (long)1e18;
          }
        }
        for (int s = (1 << Rs) - 2; s >= 0; --s)
        {
          for (int v = 0; v < Rs; ++v)
          {
            for (int u = 0; u < Rs; ++u)
            {
              dp[v, s] = Math.Min(dp[v, s], dp[u, s | 1 << u] + dist2[v, u]);
            }
          }
        }
        long min = (long)1e18;
        for (int i = 0; i < Rs; ++i)
        {
          min = Math.Min(min, dp[i, 0]);
        }
        Console.WriteLine(min);
      }
    }

    class Util
    {
      public static T[,] Gen<T>(int r, int c, T v)
      {
        var matrix = new T[r, c];
        for (int i = 0; i < r; ++i)
        {
          for (int j = 0; j < c; ++j)
          {
            matrix[i, j] = v;
          }
        }
        return matrix;
      }
      public static long[] ASum(long[] array)
      {
        var res = new long[array.Length + 1];
        for (int i = 0; i < array.Length; ++i)
        {
          res[i + 1] = res[i] + array[i];
        }
        return res;
      }
      public static long[,] ASum(long[,] matrix)
      {
        var N = matrix.GetLength(0);
        var M = matrix.GetLength(1);
        var res = new long[N + 1, M + 1];
        for(int i = 0; i < N; ++i)
        {
          for(int j = 0; j < M; ++j)
          {
            res[i + 1, j + 1] = res[i, j + 1] + res[i + 1, j] - res[i, j] + matrix[i, j];
          }
        }
        return res;
      }
      public static Dictionary<T, long> Frequency<T>(T[] array)
      {
        var dict = new Dictionary<T, long>();
        foreach (var a in array)
        {
          if (!dict.ContainsKey(a)) { dict.Add(a, 0); }
          dict[a]++;
        }
        return dict;
      }

      public static void WarshallFloyd(long[,] dist)
      {
        var N = dist.GetLength(0);
        for (int k = 0; k < N; ++k)
        {
          for (int i = 0; i < N; ++i)
          {
            for (int j = 0; j < N; ++j)
            {
              dist[i, j] = Math.Min(dist[i, j], dist[i, k] + dist[k, j]);
            }
          }
        }
      }
      public static long[,] DistFromAdj(int N, Dictionary<int, Dictionary<int, long>> adj)
      {
        var dist = new long[N, N];
        for (int i = 0; i < N; ++i)
        {
          for (int j = 0; j < N; ++j)
          {
            dist[i, j] = adj.ContainsKey(i + 1) && adj[i + 1].ContainsKey(j + 1) ? adj[i + 1][j + 1] : (long)1e18;
          }
        }
        return dist;
      }
    }

    static class Read
{
static Queue<string> queue = new Queue<string>();
static void Enqueue() { var ss = Console.ReadLine().Split(' '); foreach (var s in ss) { queue.Enqueue(s); } }
public static int Int() { if (queue.Count == 0) { Enqueue(); } return Convert.ToInt32(queue.Dequeue()); }
public static long Long() { if (queue.Count == 0) { Enqueue(); } return Convert.ToInt64(queue.Dequeue()); }
public static string Str() { if (queue.Count == 0) { Enqueue(); } return queue.Dequeue(); }
public static int[] IntN() { return Console.ReadLine().Split(' ').Select(s => Convert.ToInt32(s)).ToArray(); }
public static long[] LongN() { return Console.ReadLine().Split(' ').Select(s => Convert.ToInt64(s)).ToArray(); }
public static ulong[] ULongN() { return Console.ReadLine().Split(' ').Select(s => Convert.ToUInt64(s)).ToArray(); }
public static string[] StrN() { return Console.ReadLine().Split(' '); }
public static Tuple<int, int>[] TupleInt(int n) { List<Tuple<int, int>> list = new List<Tuple<int, int>>(); for (int i = 0; i < n; ++i) { var ab = Read.IntN(); list.Add(new Tuple<int, int>(ab[0], ab[1])); } return list.ToArray(); }
public static Tuple<long, long>[] TupleLong(int n) { List<Tuple<long, long>> list = new List<Tuple<long, long>>(); for (int i = 0; i < n; ++i) { var ab = Read.LongN(); list.Add(new Tuple<long, long>(ab[0], ab[1])); } return list.ToArray(); }
public static Tuple<string, string>[] TupleStr(int n) { List<Tuple<string, string>> list = new List<Tuple<string, string>>(); for (int i = 0; i < n; ++i) { var ab = Read.StrN(); list.Add(new Tuple<string, string>(ab[0], ab[1])); } return list.ToArray(); }
public static Tuple<double, double>[] TupleDouble(int n) { List<Tuple<double, double>> list = new List<Tuple<double, double>>(); for (int i = 0; i < n; ++i) { var ab = Read.LongN(); list.Add(new Tuple<double, double>(ab[0], ab[1])); } return list.ToArray(); }
public static long[,] LongMatrix(int r, int c) { var mat = new long[r, c]; for (int i = 0; i < r; ++i) { var x = Read.LongN(); for (int j = 0; j < c; ++j) { mat[i, j] = x[j]; } } return mat; }
public static Dictionary<int, HashSet<int>> AdjacencyList(int N, int M, bool isDirectional = false)
{
Dictionary<int, HashSet<int>> dict = new Dictionary<int, HashSet<int>>();
for (int i = 0; i <= N; ++i) { dict.Add(i, new HashSet<int>()); }
        for (int i = 0; i < M; ++i) { var ab = Read.IntN(); if (!dict[ab[0]].Contains(ab[1])) { dict[ab[0]].Add(ab[1]); } if (!isDirectional && !dict[ab[1]].Contains(ab[0])) { dict[ab[1]].Add(ab[0]); } }
        return dict;
}
public static Dictionary<int, Dictionary<int, long>> AdjacencyListWithWeight(int N, int M)
{
Dictionary<int, Dictionary<int, long>> dict = new Dictionary<int, Dictionary<int, long>>(); for (int i = 0; i <= N; ++i) { dict.Add(i, new Dictionary<int, long>()); }
for (int i = 0; i < M; ++i) { var ab = Read.IntN(); dict[ab[0]].Add(ab[1], ab[2]); dict[ab[1]].Add(ab[0], ab[2]); }
return dict;
}
}
    }
}


Measured memory_bytes: 19516