#include <bits/stdc++.h>
using namespace std;
int main() {
  int i, j, l, ans = 0;
  char ch1[2000], ch2[2000];
  gets(ch1);
  for (i = 0, j = 0; ch1[i] != NULL; i++) {
    if (ch1[i] >= 'a' && ch1[i] <= 'z') {
      ch2[j] = ch1[i];
      j++;
    }
  }
  sort(ch2, ch2 + j);
  for (i = 0; i < j - 1; i++) {
    if (ch2[i] != ch2[i + 1]) {
      ans++;
    }
  }
  if (ch2[0] == NULL && ch2[1] == NULL) {
    l = ans;
  } else if (ch2[1] == NULL) {
    l = 1;
  } else {
    l = ans + 1;
  }
  cout << l;
}
