#pragma GCC diagnostic ignored "-Wunused-result"
#pragma GCC optimize "Ofast"

#include <stdint.h>
#include <stdio.h>

uint8_t c, t[200001] = {};
int64_t n = 0, z = 0;

int main() {
  fseek(stdin, 0, 2);
  int64_t istrlen = ftell(stdin);
  uint8_t istr[istrlen], *iptr = istr;
  fseek(stdin, 0, 0);
  fread(istr, 1, istrlen, stdin);
  while ((c = *iptr++) >= '0') n = n * 10 + (c - '0');

  while (--n >= 0) {
    int32_t a = *(int32_t*)iptr;

    if ((a | 0x30303030) == a) {
      int64_t _ = *(int16_t*)(iptr + 4);

      if ((_ | 0x3030) == _) {
        a = (((((a & 0xF0F0F0F) * 0xA01) >> 8 & 0xFF00FF) * 0x640001) >> 16) * 100 + (_ & 0xF) * 10 + (_ >> 8 & 0xF);
        iptr += 7;
      }
      else if ((_ | 0x30) == _) {
        a = (((((a & 0xF0F0F0F) * 0xA01) >> 8 & 0xFF00FF) * 0x640001) >> 16) * 10 + (_ & 0xF);
        iptr += 6;
      }
      else {
        a = ((((a & 0xF0F0F0F) * 0xA01) >> 8 & 0xFF00FF) * 0x640001) >> 16;
        iptr += 5;
      }
    }
    else if ((a | 0x3030) == a) {
      uint8_t _ = *(iptr + 2);

      if (_ >= '0') {
        a = (a & 0xF) * 100 + (a >> 8 & 0xF) * 10 + (_ - '0');
        iptr += 4;
      }
      else {
        a = (a & 0xF) * 10 + (a >> 8 & 0xF);
        iptr += 3;
      }
    }
    else {
      a &= 0xF;
      iptr += 2;
    }

    if (++t[a] == 2) {
      t[a] = 0;
      ++z;
    }
  }

  printf("%ld", z);
  return 0;
}