#include <cstdio>

int compute(int x) {
  int s = 0, p;
  for(int i = 1; i <= x; i++) {
    p = 1;
    for(int j = 1; j <= i; j++)
      p = (p * i) % 10;
    s += p;
  }
  return s;
}

int main() {
  freopen("cifra.in", "r", stdin);
  freopen("cifra.out", "w", stdout);
  char *number = new char[105];
  number[0] = 0;
  scanf("%s", number);

  if(number[1] == '\0') {
    int x = number[0] - '0';
    printf("%d", compute(x) % 10);
  } else {
    int x = 0;
    while(number[x + 2] != '\0')
      x++;
    int p = (number[x] - '0') * 10 + (number[x+1] - '0');
    printf("%d", compute(p) % 10);
  }
  return 0;
}