Language: C++

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

//
#define int long long
#define pb(x) push_back(x)
#define m0(x) memset((x), 0, sizeof(x))
#define mm(x) memset((x), -1, sizeof(x))

//container
#define ALL(x) (x).begin(), (x).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define EACH(i, c) for (typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define EXIST(s, e) ((s).find(e) != (s).end())
#define UNIQUE(v) (v).erase(unique((v).begin(), (v).end()), (v).end());
#define PERM(c) \
  sort(ALL(c)); \
  for (bool c##p = 1; c##p; c##p = next_permutation(ALL(c)))

// debug
#define GET_VAR_NAME(variable) #variable
#define test(x) cout << GET_VAR_NAME(x) << " = " << x << endl;

// bit_macro
#define bit(n) (1LL << (n))
#define bitset(a, b) (a) |= (1 << (b))
#define bitunset(a, b) (a) |= ~(1 << (b))
#define bitcheck(a, b) ((((a) >> (b)) & 1) == 1)
#define bitcount(a) __builtin_popcountll((a))

//typedef
typedef long long lint;
typedef unsigned long long ull;
typedef complex<long double> Complex;
typedef pair<int, int> P;
typedef tuple<int, int, int> TP;
typedef vector<int> vec;
typedef vector<vec> mat;

//constant
const int INF = (int)1e18;
const int MOD = (int)1e9 + 7;
const double EPS = (double)1e-10;
const int dx[] = { -1, 0, 0, 1, 0, -1, -1, 1, 1 };
const int dy[] = { 0, -1, 1, 0, 0, 1, -1, 1, -1 };

//
template <typename T>
void chmax(T &a, T b) { a = max(a, b); }
template <typename T>
void chmin(T &a, T b) { a = min(a, b); }
//
inline int toInt(string s) {
	int v;
	istringstream sin(s);
	sin >> v;
	return v;
}
template <class T>
inline string toString(T x) {
	ostringstream sout;
	sout << x;
	return sout.str();
}

//
struct Accelerate_Cin {
	Accelerate_Cin() {
		cin.tie(0);
		ios::sync_with_stdio(0);
		cout << fixed << setprecision(20);
	};
};

int H, W; 
string s[410];
int x = 0, y = 0;//xが黒yが白
bool visited[410][410];
void dfs(int Y,int X) {
	if (visited[Y][X]==true)return;
	visited[Y][X] = true;
	for (int k = 0; k < 4; ++k) {
		int ny = Y + dy[k], nx = X + dx[k];
		if (ny >= H || ny < 0 || nx >= W || nx < 0 || visited[ny][nx] || s[ny][nx] == s[Y][X])continue;
		dfs(ny, nx);
	}
	if (s[Y][X] == '#') {
		x++;
	}
	else {
		y++;
	}
	return;
}
signed main() {
	cin >> H >> W;
	REP(i, H)cin >> s[i];
	ll ans = 0;
	for (int i = 0; i < H; ++i) {
		for (int j = 0; j < W; ++j) {
			dfs(i, j);
			ans += x * y;
			x = 0;
			y = 0;
		}
	}
	cout << ans << endl;
	return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:99:13: error: 'i' was not declared in this scope
   99 |         REP(i, H)cin >> s[i];
      |             ^
a.cc:99:9: error: 'REP' was not declared in this scope
   99 |         REP(i, H)cin >> s[i];
      |         ^~~
a.cc:100:9: error: 'll' was not declared in this scope; did you mean 'ull'?
  100 |         ll ans = 0;
      |         ^~
      |         ull
a.cc:104:25: error: 'ans' was not declared in this scope; did you mean 'abs'?
  104 |                         ans += x * y;
      |                         ^~~
      |                         abs
a.cc:109:17: error: 'ans' was not declared in this scope; did you mean 'abs'?
  109 |         cout << ans << endl;
      |                 ^~~
      |                 abs