Compilare: user.cpp: In function ‘int main()’: user.cpp:38:39: warning: array subscript has type ‘char’ [-Wchar-subscripts] for(i = 1; i <= N; ++i) pos[ s[i] ][ ++pos[ s[i] ][0] ] = i; ^ user.cpp:38:54: warning: array subscript has type ‘char’ [-Wchar-subscripts] for(i = 1; i <= N; ++i) pos[ s[i] ][ ++pos[ s[i] ][0] ] = i; ^ user.cpp:44:23: warning: array subscript has type ‘char’ [-Wchar-subscripts] ++frecv[ s[i] ]; ^ user.cpp:29:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bignumber.in","r",stdin); ^ user.cpp:30:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bignumber.out","w",stdout); ^ user.cpp:34:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n",&N,&X); ^ user.cpp:35:32: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets( s+1, NMax-1, stdin ); ^