#include <bits/stdc++.h>
using namespace std;
string s;
bool atted, dotted, goned;
int cntu, cnth = -1, cntr = -1, cntd = -1;
int main() {
  cin >> s;
  for (int i = 0; i < ((int)(s).size()); i++) {
    if (!atted && s[i] == '@')
      atted = 1;
    else if (atted && !goned && s[i] == '.' && s[i - 1] != '.' &&
             s[i - 1] != '@' && cntd <= 16)
      dotted = 1, cntd = -1;
    else if (atted && !goned && s[i] == '/')
      goned = 1;
    else if ((!atted || goned) && s[i] == '.')
      return puts("NO"), 0;
    else if (!isalnum(s[i]) && s[i] != '_')
      return puts("NO"), 0;
    if (!atted)
      cntu++;
    else if (!goned)
      cnth++, cntd++;
    else
      cntr++;
  }
  if (cntd == 0) return puts("NO"), 0;
  if (cntu < 1 || cntu > 16 || cnth < 1 || cnth > 32 || goned && cntr < 1 ||
      cntr > 32)
    return puts("NO"), 0;
  return puts("YES"), 0;
}
