Compilare: user.cpp: In function ‘int main()’: user.cpp:93:22: warning: array subscript has type ‘char’ [-Wchar-subscripts] fgets(1 + a[i], N, f); ^ user.cpp:89:32: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d%d\n", &n, &m); ^ user.cpp:93:30: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(1 + a[i], N, f); ^