Language: C++

#include <bits/stdc++.h>
using namespace std;

typedef long long int LL;
typedef double DB;
typedef float FL;
typedef vector<LL> VL;
typedef tuple<LL, LL, LL> TTL;
typedef tuple<LL, LL, LL, LL> TFL;
const LL N=pow(10, 9)+7;

#define FAST ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define RW(a, b) freopen(a, "r", stdin); freopen(b, "w", stdout);
#define V(a) vector<a>
#define P(a) pair<a, a>
#define endl "\n"
#define REP(i, a, b, k) for(LL i=a; i<b; i+=k)
#define RREP(i, a, b, k) for(LL i=a; i>b; i-=k)
#define PB push_back
#define PF pop_front
#define MP make_pair
#define MT make_tuple
#define G(i, a) get<i>(a)
#define F first
#define S second

LL MIN(LL a, LL b) // returns the minimum of two numbers a and b
{
    if(a<b) return a;
    else return b;
}

LL MAX(LL a, LL b) // returns the maximum of two numbers a and b
{ 
    if(a>b) return a;
    else return b;
}

void swap(LL *a, LL *b) // swaps the two numbers
{ 
    LL *x=a;
    a=b;
    b=x;
}

LL SOD(LL a) // returns sum of digits of a decimal number
{ 
    LL sum=0;
    while(a!=0)
    {
        sum=sum+a%10;
        a=a/10;
    }
    return sum;
}

LL NUM1(LL a) // returns the count of number of 1's in binary representation of a decimal number
{ 
    LL s=0;
    while(a!=0)
    {
        if(a%2==1)
        {
            s++;
        }
        a=a/2;
    }
    return s;
}

LL BMOD(string s, LL a) // returns remainder when a binary number in string s is divided by a decimal number a
{ 
    LL res=0;
    REP(i, 0, s.length(), 1) res=(10*res+(LL)s[i]-'0')%a;
    return res;
}

LL NOD(LL n) // returns the number of divisors of n
{ 
    LL ans=0, x=sqrt(n);
    if(x%1==0)
    {
        REP(i, 1, x+1, 1)
        {
            if(n%i==0) ans+=2;
            if(n==i*i) ans--;
        }
    }
    else
    {
        REP(i, 0, x, 1) if(n%i==0) ans+=2;
    }
    return ans;
}

VL PF(LL n) // returns all the prime factors of a number n in a vector
{   
    VL v;
    while(n%2==0)  
    {  
        v.PB(2); 
        n = n/2;  
    }  
    REP(i, 3, sqrt(n)+1, 2)
    {  
        while(n%i==0)  
        {  
            v.PB(i);
            n = n/i;  
        }  
    }
    if (n>2) v.PB(n);  
    return v;
}  

LL FACT(LL n) // returns factorial of a number n
{ 
    if (n==0) 
    return 1; 
    return n*FACT(n-1); 
}

DB DIST(LL x1, LL y1, LL x2, LL y2) // returns the euler distance between two points in a 2D plane
{ 
    LL dx=x1-x2, dy=y1-y2;
    return(pow(dx*dx+dy*dy, 0.5));
}

VL SOE(LL n) // returns a vector containing all the primes upto the number n 
{
    VL v;
    bool prime[n+1]; 
    memset(prime, true, sizeof(prime)); 
    for(LL p=2; p*p<=n; p++) 
    { 
        if(prime[p]==true) 
        { 
            for(LL i=p*p; i<=n; i += p) 
                prime[i]=false; 
        } 
    }
    for(LL p=2; p<=n; p++) 
       if(prime[p]) 
            v.PB(p);
    return v; 
}

LL GCD(LL a, LL b) // returns gcd of a and b
{ 
    if (b == 0) 
        return a; 
    return GCD(b, a % b); 
} 

LL LCM(LL arr[], LL n) // returns lcm of a and b
{
    LL ans = arr[0]; 
    for(LL i = 1; i < n; i++) 
        ans=(((arr[i] * ans))/(GCD(arr[i], ans))); 
    return ans; 
}

LL MODEXP(LL x, LL n, LL m) // return modular exponential of x with power n wrt m
{ 
    if (n == 0) return 1;
    else if (n % 2 == 0) return MODEXP((x * x) % m, n / 2, m); 
    else return (x * MODEXP((x * x) % m, (n - 1) / 2, m) % m); 
} 
  
LL GFM(LL a, LL b, LL m) // returns mod of a fraction wrt m
{ 
    LL c = GCD(a, b); 
    a = a / c; 
    b = b / c; 
    LL d = MODEXP(b, m - 2, m); 
    LL ans = ((a % m) * (d % m)) % m; 
    return ans; 
}

LL NOSWP(LL arr[], LL n, LL k) // subarrays with product k
{ 
    LL start = 0, endval = 0, p = 1, countOnes = 0, res = 0; 
    while (endval < n)  
    { 
        p *= (arr[endval]); 
        if(p > k) 
        { 
            while(start <= endval && p > k) 
            { 
                p /= arr[start]; 
                start++; 
            } 
        } 
        if(p == k) 
        { 
            countOnes = 0; 
            while(endval + 1 < n && arr[endval + 1] == 1) 
            { 
                countOnes++; 
                endval++; 
            } 
            res += (countOnes + 1); 
            while(start <= endval && arr[start] == 1 && k!=1) 
            { 
                res += (countOnes + 1); 
                start++; 
            } 
            p /= arr[start]; 
            start++; 
        } 
        endval++; 
    } 
    return res; 
} 

LL SOLVE(LL T)
{
    LL n, ans=0;
    string s;
    cin>>n>>s;
    V(TTL) v;
    REP(i, 1, n+1, 1)
    {
        REP(j, i+1, n+1, 1)
        {
            REP(k, j+1, n+1, 1)
            {
                if(i+k!=2*j) v.PB(make_tuple(i, j, k));
            }
        }
    }
    REP(i, 0, v.size(), 1)
    {
        char a=s[get<0>(v[i])-1], b=s[get<1>(v[i])-1], c=s[get<2>(v[i])-1];
        if(a!=b&&b!=c&&a!=c) ans++;
    }
    cout<<ans<<endl;
    return 0;
}

int main()
{
    // FAST // untie cin and cout
    // RW("in.txt", "out.txt") // I/O in text file
    LL T=1;
    // cin >> T;
    REP(i, 0, T, 1) SOLVE(i+1);
    return 0;
}#include <bits/stdc++.h>
using namespace std;

typedef long long int LL;
typedef double DB;
typedef float FL;
typedef vector<LL> VL;
typedef tuple<LL, LL, LL> TTL;
typedef tuple<LL, LL, LL, LL> TFL;
const LL N=pow(10, 9)+7;

#define FAST ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define RW(a, b) freopen(a, "r", stdin); freopen(b, "w", stdout);
#define V(a) vector<a>
#define P(a) pair<a, a>
#define endl "\n"
#define REP(i, a, b, k) for(LL i=a; i<b; i+=k)
#define RREP(i, a, b, k) for(LL i=a; i>b; i-=k)
#define PB push_back
#define PF pop_front
#define MP make_pair
#define MT make_tuple
#define G(i, a) get<i>(a)
#define F first
#define S second

LL MIN(LL a, LL b) // returns the minimum of two numbers a and b
{
    if(a<b) return a;
    else return b;
}

LL MAX(LL a, LL b) // returns the maximum of two numbers a and b
{ 
    if(a>b) return a;
    else return b;
}

void swap(LL *a, LL *b) // swaps the two numbers
{ 
    LL *x=a;
    a=b;
    b=x;
}

LL SOD(LL a) // returns sum of digits of a decimal number
{ 
    LL sum=0;
    while(a!=0)
    {
        sum=sum+a%10;
        a=a/10;
    }
    return sum;
}

LL NUM1(LL a) // returns the count of number of 1's in binary representation of a decimal number
{ 
    LL s=0;
    while(a!=0)
    {
        if(a%2==1)
        {
            s++;
        }
        a=a/2;
    }
    return s;
}

LL BMOD(string s, LL a) // returns remainder when a binary number in string s is divided by a decimal number a
{ 
    LL res=0;
    REP(i, 0, s.length(), 1) res=(10*res+(LL)s[i]-'0')%a;
    return res;
}

LL NOD(LL n) // returns the number of divisors of n
{ 
    LL ans=0, x=sqrt(n);
    if(x%1==0)
    {
        REP(i, 1, x+1, 1)
        {
            if(n%i==0) ans+=2;
            if(n==i*i) ans--;
        }
    }
    else
    {
        REP(i, 0, x, 1) if(n%i==0) ans+=2;
    }
    return ans;
}

VL PF(LL n) // returns all the prime factors of a number n in a vector
{   
    VL v;
    while(n%2==0)  
    {  
        v.PB(2); 
        n = n/2;  
    }  
    REP(i, 3, sqrt(n)+1, 2)
    {  
        while(n%i==0)  
        {  
            v.PB(i);
            n = n/i;  
        }  
    }
    if (n>2) v.PB(n);  
    return v;
}  

LL FACT(LL n) // returns factorial of a number n
{ 
    if (n==0) 
    return 1; 
    return n*FACT(n-1); 
}

DB DIST(LL x1, LL y1, LL x2, LL y2) // returns the euler distance between two points in a 2D plane
{ 
    LL dx=x1-x2, dy=y1-y2;
    return(pow(dx*dx+dy*dy, 0.5));
}

VL SOE(LL n) // returns a vector containing all the primes upto the number n 
{
    VL v;
    bool prime[n+1]; 
    memset(prime, true, sizeof(prime)); 
    for(LL p=2; p*p<=n; p++) 
    { 
        if(prime[p]==true) 
        { 
            for(LL i=p*p; i<=n; i += p) 
                prime[i]=false; 
        } 
    }
    for(LL p=2; p<=n; p++) 
       if(prime[p]) 
            v.PB(p);
    return v; 
}

LL GCD(LL a, LL b) // returns gcd of a and b
{ 
    if (b == 0) 
        return a; 
    return GCD(b, a % b); 
} 

LL LCM(LL arr[], LL n) // returns lcm of a and b
{
    LL ans = arr[0]; 
    for(LL i = 1; i < n; i++) 
        ans=(((arr[i] * ans))/(GCD(arr[i], ans))); 
    return ans; 
}

LL MODEXP(LL x, LL n, LL m) // return modular exponential of x with power n wrt m
{ 
    if (n == 0) return 1;
    else if (n % 2 == 0) return MODEXP((x * x) % m, n / 2, m); 
    else return (x * MODEXP((x * x) % m, (n - 1) / 2, m) % m); 
} 
  
LL GFM(LL a, LL b, LL m) // returns mod of a fraction wrt m
{ 
    LL c = GCD(a, b); 
    a = a / c; 
    b = b / c; 
    LL d = MODEXP(b, m - 2, m); 
    LL ans = ((a % m) * (d % m)) % m; 
    return ans; 
}

LL NOSWP(LL arr[], LL n, LL k) // subarrays with product k
{ 
    LL start = 0, endval = 0, p = 1, countOnes = 0, res = 0; 
    while (endval < n)  
    { 
        p *= (arr[endval]); 
        if(p > k) 
        { 
            while(start <= endval && p > k) 
            { 
                p /= arr[start]; 
                start++; 
            } 
        } 
        if(p == k) 
        { 
            countOnes = 0; 
            while(endval + 1 < n && arr[endval + 1] == 1) 
            { 
                countOnes++; 
                endval++; 
            } 
            res += (countOnes + 1); 
            while(start <= endval && arr[start] == 1 && k!=1) 
            { 
                res += (countOnes + 1); 
                start++; 
            } 
            p /= arr[start]; 
            start++; 
        } 
        endval++; 
    } 
    return res; 
} 

LL SOLVE(LL T)
{
    LL n, ans=0;
    string s;
    cin>>n>>s;
    V(TTL) v;
    REP(i, 1, n+1, 1)
    {
        REP(j, i+1, n+1, 1)
        {
            REP(k, j+1, n+1, 1)
            {
                if(i+k!=2*j) v.PB(make_tuple(i, j, k));
            }
        }
    }
    REP(i, 0, v.size(), 1)
    {
        char a=s[get<0>(v[i])-1], b=s[get<1>(v[i])-1], c=s[get<2>(v[i])-1];
        if(a!=b&&b!=c&&a!=c) ans++;
    }
    cout<<ans<<endl;
    return 0;
}

int main()
{
    // FAST // untie cin and cout
    // RW("in.txt", "out.txt") // I/O in text file
    LL T=1;
    // cin >> T;
    REP(i, 0, T, 1) SOLVE(i+1);
    return 0;
}

Compiler output:
a.cc:249:2: error: stray '#' in program
  249 | }#include <bits/stdc++.h>
      |  ^
a.cc:249:3: error: 'include' does not name a type
  249 | }#include <bits/stdc++.h>
      |   ^~~~~~~
a.cc:258:10: error: redefinition of 'const LL N'
  258 | const LL N=pow(10, 9)+7;
      |          ^
a.cc:10:10: note: 'const LL N' previously defined here
   10 | const LL N=pow(10, 9)+7;
      |          ^
a.cc:275:4: error: redefinition of 'LL MIN(LL, LL)'
  275 | LL MIN(LL a, LL b) // returns the minimum of two numbers a and b
      |    ^~~
a.cc:27:4: note: 'LL MIN(LL, LL)' previously defined here
   27 | LL MIN(LL a, LL b) // returns the minimum of two numbers a and b
      |    ^~~
a.cc:281:4: error: redefinition of 'LL MAX(LL, LL)'
  281 | LL MAX(LL a, LL b) // returns the maximum of two numbers a and b
      |    ^~~
a.cc:33:4: note: 'LL MAX(LL, LL)' previously defined here
   33 | LL MAX(LL a, LL b) // returns the maximum of two numbers a and b
      |    ^~~
a.cc:287:6: error: redefinition of 'void swap(LL*, LL*)'
  287 | void swap(LL *a, LL *b) // swaps the two numbers
      |      ^~~~
a.cc:39:6: note: 'void swap(LL*, LL*)' previously defined here
   39 | void swap(LL *a, LL *b) // swaps the two numbers
      |      ^~~~
a.cc:294:4: error: redefinition of 'LL SOD(LL)'
  294 | LL SOD(LL a) // returns sum of digits of a decimal number
      |    ^~~
a.cc:46:4: note: 'LL SOD(LL)' previously defined here
   46 | LL SOD(LL a) // returns sum of digits of a decimal number
      |    ^~~
a.cc:305:4: error: redefinition of 'LL NUM1(LL)'
  305 | LL NUM1(LL a) // returns the count of number of 1's in binary representation of a decimal number
      |    ^~~~
a.cc:57:4: note: 'LL NUM1(LL)' previously defined here
   57 | LL NUM1(LL a) // returns the count of number of 1's in binary representation of a decimal number
      |    ^~~~
a.cc:319:4: error: redefinition of 'LL BMOD(std::string, LL)'
  319 | LL BMOD(string s, LL a) // returns remainder when a binary number in string s is divided by a decimal number a
      |    ^~~~
a.cc:71:4: note: 'LL BMOD(std::string, LL)' previously defined here
   71 | LL BMOD(string s, LL a) // returns remainder when a binary number in string s is divided by a decimal number a
      |    ^~~~
a.cc:326:4: error: redefinition of 'LL NOD(LL)'
  326 | LL NOD(LL n) // returns the number of divisors of n
      |    ^~~
a.cc:78:4: note: 'LL NOD(LL)' previously defined here
   78 | LL NOD(LL n) // returns the number of divisors of n
      |    ^~~
a.cc:268:12: error: redefinition of 'VL pop_front(LL)'
  268 | #define PF pop_front
      |            ^~~~~~~~~
a.cc:344:4: note: in expansion of macro 'PF'
  344 | VL PF(LL n) // returns all the prime factors of a number n in a vector
      |    ^~
a.cc:20:12: note: 'VL pop_front(LL)' previously defined here
   20 | #define PF pop_front
      |            ^~~~~~~~~
a.cc:96:4: note: in expansion of macro 'PF'
   96 | VL PF(LL n) // returns all the prime factors of a number n in a vector
      |    ^~
a.cc:364:4: error: redefinition of 'LL FACT(LL)'
  364 | LL FACT(LL n) // returns factorial of a number n
      |    ^~~~
a.cc:116:4: note: 'LL FACT(LL)' previously defined here
  116 | LL FACT(LL n) // returns factorial of a number n
      |    ^~~~
a.cc:371:4: error: redefinition of 'DB DIST(LL, LL, LL, LL)'
  371 | DB DIST(LL x1, LL y1, LL x2, LL y2) // returns the euler distance between two points in a 2D plane
      |    ^~~~
a.cc:123:4: note: 'DB DIST(LL, LL, LL, LL)' previously defined here
  123 | DB DIST(LL x1, LL y1, LL x2, LL y2) // returns the euler distance between two points in a 2D plane
      |    ^~~~
a.cc:377:4: error: redefinition of 'VL SOE(LL)'
  377 | VL SOE(LL n) // returns a vector containing all the primes upto the number n
      |    ^~~
a.cc:129:4: note: 'VL SOE(LL)' previously defined here
  129 | VL SOE(LL n) // returns a vector containing all the primes upto the number n
      |    ^~~
a.cc:396:4: error: redefinition of 'LL GCD(LL, LL)'
  396 | LL GCD(LL a, LL b) // returns gcd of a and b
      |    ^~~
a.cc:148:4: note: 'LL GCD(LL, LL)' previously defined here
  148 | LL GCD(LL a, LL b) // returns gcd of a and b
      |    ^~~
a.cc:403:4: error: redefinition of 'LL LCM(LL*, LL)'
  403 | LL LCM(LL arr[], LL n) // returns lcm of a and b
      |    ^~~
a.cc:155:4: note: 'LL LCM(LL*, LL)' previously defined here
  155 | LL LCM(LL arr[], LL n) // returns lcm of a and b
      |    ^~~
a.cc:411:4: error: redefinition of 'LL MODEXP(LL, LL, LL)'
  411 | LL MODEXP(LL x, LL n, LL m) // return modular exponential of x with power n wrt m
      |    ^~~~~~
a.cc:163:4: note: 'LL MODEXP(LL, LL, LL)' previously defined here
  163 | LL MODEXP(LL x, LL n, LL m) // return modular exponential of x with power n wrt m
      |    ^~~~~~
a.cc:418:4: error: redefinition of 'LL GFM(LL, LL, LL)'
  418 | LL GFM(LL a, LL b, LL m) // returns mod of a fraction wrt m
      |    ^~~
a.cc:170:4: note: 'LL GFM(LL, LL, LL)' previously defined here
  170 | LL GFM(LL a, LL b, LL m) // returns mod of a fraction wrt m
      |    ^~~
a.cc:428:4: error: redefinition of 'LL NOSWP(LL*, LL, LL)'
  428 | LL NOSWP(LL arr[], LL n, LL k) // subarrays with product k
      |    ^~~~~
a.cc:180:4: note: 'LL NOSWP(LL*, LL, LL)' previously defined here
  180 | LL NOSWP(LL arr[], LL n, LL k) // subarrays with product k
      |    ^~~~~
a.cc:464:4: error: redefinition of 'LL SOLVE(LL)'
  464 | LL SOLVE(LL T)
      |    ^~~~~
a.cc:216:4: note: 'LL SOLVE(LL)' previously defined here
  216 | LL SOLVE(LL T)
      |    ^~~~~
a.cc:489:5: error: redefinition of 'int main()'
  489 | int main()
      |     ^~~~
a.cc:241:5: note: 'int main()' previously defined here
  241 | int main()
      |     ^~~~