Compilare: user.cpp: In function ‘int main()’: user.cpp:21:12: warning: array subscript has type ‘char’ [-Wchar-subscripts] k[a][b]=k[b][a]=1; ^ user.cpp:21:15: warning: array subscript has type ‘char’ [-Wchar-subscripts] k[a][b]=k[b][a]=1; ^ user.cpp:21:20: warning: array subscript has type ‘char’ [-Wchar-subscripts] k[a][b]=k[b][a]=1; ^ user.cpp:21:23: warning: array subscript has type ‘char’ [-Wchar-subscripts] k[a][b]=k[b][a]=1; ^ user.cpp:14:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("nrcuv.in","r",stdin); ^ user.cpp:15:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("nrcuv.out","w",stdout); ^ user.cpp:16:27: 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:18:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%c %c\n",&a,&b); ^