#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:1000000000")
using namespace std;
const int maxn = (int)1e6 + 10;
bool used[maxn];
int main() {
  int n;
  cin >> n;
  int y = 0;
  for (int i = 0; i < n; i++) {
    int x;
    scanf("%d", &x);
    used[x] = true;
  }
  int z = 25 - n;
  int pos = 1;
  while (z > 0) {
    while (used[pos]) {
      pos++;
    }
    used[pos] = true;
    z--;
  }
  int ans = 0;
  for (int i = 0; i < maxn; i++) {
    if (used[i]) {
      ans = i;
    }
  }
  cout << ans - 25 << endl;
  return 0;
}
