#include <bits/stdc++.h>
int read() {
  int x = 0, y = 1;
  char ch = getchar();
  while (ch > '9' || ch < '0') {
    if (ch == '-') y = -1;
    ch = getchar();
  }
  while (ch <= '9' && ch >= '0')
    x = (x << 3) + (x << 1) + ch - '0', ch = getchar();
  return x * y;
}
void print(int x) {
  if (x < 0) {
    putchar('0');
    return;
  }
  if (x < 10) {
    putchar(x + '0');
    return;
  }
  print(x / 10);
  putchar(x % 10 + '0');
}
int n, x, maxx;
int main() {
  n = read();
  for (int _ = 0; _ < n; _++) x = read(), maxx = maxx > x ? maxx : x;
  print(maxx - 25);
  return 0;
}
