Compilare: user.cpp: In function ‘void read()’: user.cpp:25: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp:29: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void df(int)’: user.cpp:42: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void solve()’: user.cpp:61: warning: comparison between signed and unsigned integer expressions user.cpp:64: warning: array subscript has type ‘char’