Compilare: main.cpp: In function 'int main()': main.cpp:25:33: warning: this 'for' clause does not guard... [-Wmisleading-indentation] for (int i = 0; i < n; i++) for (int j = 0; j < m; j++) ^~~ main.cpp:26:39: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'for' in >> A[i][j], B[i][j] = N*N; a(B) = 0; ^ main.cpp:28:25: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses] for (P d: D) if (0 <= f.x and f.x < n and 0 <= f.y and f.y < m) ^