#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, aa = 0, ab = 0, ac = 0, ad = 0, ae = 0, af = 0, ag = 0, ah = 0, ai = 0,
         aj = 0, ak = 0, al = 0, am = 0, an = 0, ao = 0, ap = 0, aq = 0, ar = 0,
         as = 0, at1 = 0, au = 0, av = 0, aw = 0, ax = 0, ay = 0, az = 0;
  char b;
  cin >> a;
  for (int i = 1; i <= a; i++) {
    cin >> b;
    if ((int(b) == 65) || (int(b) == 97)) {
      aa++;
    }
    if ((int(b) == 66) || (int(b) == 98)) {
      ab++;
    }
    if ((int(b) == 67) || (int(b) == 99)) {
      ac++;
    }
    if ((int(b) == 68) || (int(b) == 100)) {
      ad++;
    }
    if ((int(b) == 69) || (int(b) == 101)) {
      ae++;
    }
    if ((int(b) == 70) || (int(b) == 102)) {
      af++;
    }
    if ((int(b) == 71) || (int(b) == 103)) {
      ag++;
    }
    if ((int(b) == 72) || (int(b) == 104)) {
      ah++;
    }
    if ((int(b) == 73) || (int(b) == 105)) {
      ai++;
    }
    if ((int(b) == 74) || (int(b) == 106)) {
      aj++;
    }
    if ((int(b) == 75) || (int(b) == 107)) {
      ak++;
    }
    if ((int(b) == 76) || (int(b) == 108)) {
      al++;
    }
    if ((int(b) == 77) || (int(b) == 109)) {
      am++;
    }
    if ((int(b) == 78) || (int(b) == 110)) {
      an++;
    }
    if ((int(b) == 79) || (int(b) == 111)) {
      ao++;
    }
    if ((int(b) == 80) || (int(b) == 112)) {
      ap++;
    }
    if ((int(b) == 81) || (int(b) == 113)) {
      aq++;
    }
    if ((int(b) == 82) || (int(b) == 114)) {
      ar++;
    }
    if ((int(b) == 83) || (int(b) == 115)) {
      as++;
    }
    if ((int(b) == 84) || (int(b) == 116)) {
      at1++;
    }
    if ((int(b) == 85) || (int(b) == 117)) {
      au++;
    }
    if ((int(b) == 86) || (int(b) == 118)) {
      av++;
    }
    if ((int(b) == 87) || (int(b) == 119)) {
      aw++;
    }
    if ((int(b) == 88) || (int(b) == 120)) {
      ax++;
    }
    if ((int(b) == 89) || (int(b) == 121)) {
      ay++;
    }
    if ((int(b) == 90) || (int(b) == 122)) {
      az++;
    }
  }
  if ((aa != 0) && (ab != 0) && (ac != 0) && (ad != 0) && (ae != 0) &&
      (af != 0) && (ag != 0) && (ah != 0) && (ai != 0) && (aj != 0) &&
      (ak != 0) && (al != 0) && (am != 0) && (an != 0) && (ao != 0) &&
      (ap != 0) && (aq != 0) && (ar != 0) && (as != 0) && (at1 != 0) &&
      (au != 0) && (av != 0) && (aw != 0) && (ax != 0) && (ay != 0) &&
      (az != 0)) {
    cout << "YES";
  } else {
    cout << "NO";
  }
  return 0;
}
