CodeForces A. Meeting of Old Friends

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 typedef long long ll;
 4 
 5 int main()
 6 {
 7     ll a[5], e;
 8     ll sum = 0;
 9     for (int i = 1; i <= 4; i++)
10     {
11         scanf("%lld ", &a[i]);
12     }
13     scanf("%lld", &e);
14     if (a[2] < a[3] || a[4] < a[1])
15     {
16         cout << 0;
17         return 0;
18     }
19     else
20     {
21         sort(a + 1, a + 5);
22         sum = a[3] - a[2] + 1;
23         if (e >= a[2] && e <= a[3])
24         {
25             sum--;
26         }
27         cout << sum << endl;
28     }
29     
30     return 0;
31 }