#pragma GCC optimize ("Ofast")
#include<bits/stdc++.h>
using namespace std;
void *wmem;
char memarr[96000000];
inline void rd(int &x){
  int k;
  int m=0;
  x=0;
  for(;;){
    k = getchar_unlocked();
    if(k=='-'){
      m=1;
      break;
    }
    if('0'<=k&&k<='9'){
      x=k-'0';
      break;
    }
  }
  for(;;){
    k = getchar_unlocked();
    if(k<'0'||k>'9'){
      break;
    }
    x=x*10+k-'0';
  }
  if(m){
    x=-x;
  }
}
inline void rd(char &c){
  int i;
  for(;;){
    i = getchar_unlocked();
    if(i!=' '&&i!='\n'&&i!='\r'&&i!='\t'&&i!=EOF){
      break;
    }
  }
  c = i;
}
inline int rd(char c[]){
  int i;
  int sz = 0;
  for(;;){
    i = getchar_unlocked();
    if(i!=' '&&i!='\n'&&i!='\r'&&i!='\t'&&i!=EOF){
      break;
    }
  }
  c[sz++] = i;
  for(;;){
    i = getchar_unlocked();
    if(i==' '||i=='\n'||i=='\r'||i=='\t'||i==EOF){
      break;
    }
    c[sz++] = i;
  }
  c[sz]='\0';
  return sz;
}
inline void wt_L(char a){
  putchar_unlocked(a);
}
inline void wt_L(int x){
  int s=0;
  int m=0;
  char f[10];
  if(x<0){
    m=1;
    x=-x;
  }
  while(x){
    f[s++]=x%10;
    x/=10;
  }
  if(!s){
    f[s++]=0;
  }
  if(m){
    putchar_unlocked('-');
  }
  while(s--){
    putchar_unlocked(f[s]+'0');
  }
}
inline void wt_L(unsigned x){
  int s=0;
  char f[10];
  while(x){
    f[s++]=x%10;
    x/=10;
  }
  if(!s){
    f[s++]=0;
  }
  while(s--){
    putchar_unlocked(f[s]+'0');
  }
}
inline void wt_L(long long x){
  int s=0;
  int m=0;
  char f[20];
  if(x<0){
    m=1;
    x=-x;
  }
  while(x){
    f[s++]=x%10;
    x/=10;
  }
  if(!s){
    f[s++]=0;
  }
  if(m){
    putchar_unlocked('-');
  }
  while(s--){
    putchar_unlocked(f[s]+'0');
  }
}
inline void wt_L(unsigned long long x){
  int s=0;
  char f[21];
  while(x){
    f[s++]=x%10;
    x/=10;
  }
  if(!s){
    f[s++]=0;
  }
  while(s--){
    putchar_unlocked(f[s]+'0');
  }
}
inline void wt_L(double x){
  printf("%.15f",x);
}
inline void wt_L(const char c[]){
  int i=0;
  for(i=0;c[i]!='\0';i++){
    putchar_unlocked(c[i]);
  }
}
inline void wt_L(string &x){
  int i=0;
  for(i=0;x[i]!='\0';i++){
    putchar_unlocked(x[i]);
  }
}
template<class T> int KMP(T A[], int As, T B[], int Bs, int res[] = NULL, int *fail = (int*)wmem){
  int i;
  int k;
  int cnt = 0;
  k = fail[0] = -1;
  for(i=(0);i<(Bs);i++){
    while(k>=0 && B[k]!=B[i]){
      k = fail[k];
    }
    fail[i+1] = ++k;
  }
  if(res != NULL){
    for(i=(0);i<(As);i++){
      res[i] = 0;
    }
  }
  k = 0;
  for(i=(0);i<(As);i++){
    while(k >= 0 && B[k] != A[i]){
      k = fail[k];
    }
    k++;
    if(k == Bs){
      cnt++;
      if(res != NULL){
        res[i-Bs+1] = 1;
      }
      k = fail[k];
    }
  }
  return cnt;
}
template<class T, class S> int KMP(T A[], int As, T B[], int Bs, S res[], int *fail = (int*)wmem){
  int i;
  int k;
  int cnt = 0;
  k = fail[0] = -1;
  for(i=(0);i<(Bs);i++){
    while(k>=0 && B[k]!=B[i]){
      k = fail[k];
    }
    fail[i+1] = ++k;
  }
  if(res != NULL){
    for(i=(0);i<(As);i++){
      res[i] = 0;
    }
  }
  k = 0;
  for(i=(0);i<(As);i++){
    while(k >= 0 && B[k] != A[i]){
      k = fail[k];
    }
    k++;
    if(k == Bs){
      cnt++;
      if(res != NULL){
        res[i-Bs+1] = 1;
      }
      k = fail[k];
    }
  }
  return cnt;
}
int N;
char S[52];
char abc[4] = "ABC";
int main(){
  wmem = memarr;
  rd(N);
  rd(S);
  wt_L(KMP(S,N,abc,3));
  wt_L('\n');
  return 0;
}
// cLay varsion 20200112-1

// --- original code ---
// int N;
// char S[52], abc[4] = "ABC";
// {
//   rd(N,S);
//   wt(KMP(S,N,abc,3));
// }


Measured memory_bytes: 256