AC 250, tried atcoder virtual contest, wasn't even half bad

atcoder/beginner_contests/250/b.cpp

@@ -0,0 +1,34 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+
+int main(){
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+
+    int n, a, b;
+    cin >> n >> a >> b;
+
+    bool color = true;
+
+    for(int vertical_tiles = 0; vertical_tiles < n; ++vertical_tiles){
+        for(int vertical_length = 0; vertical_length < a; ++vertical_length){
+            for(int horizontal_tiles = 0; horizontal_tiles < n; ++horizontal_tiles){
+                for(int horizontal_length = 0; horizontal_length < b; ++horizontal_length){
+                    cout << (color ? "." : "#");
+                }
+                color = !color;
+            } 
+            cout << '\n';
+            if(n % 2 != 0){
+                color = !color;
+            }
+        }
+        color = !color;
+    }
+
+    cout << flush;
+
+    return 0;
+}