Compilare: user.cpp: In function ‘int main()’: user.cpp:33:72: warning: array subscript has type ‘char’ [-Wchar-subscripts] s[msk] = s[msk ^ (1 << nonZeroBit[msk])] + a[i][nonZeroBit[msk]]; ^ user.cpp:12:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("karma.in", "r", stdin); ^ user.cpp:13:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("karma.out", "w", stdout); ^ user.cpp:15:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d\n", &N, &M); ^ user.cpp:26:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%s\n", sir); ^