Compilare: user.cpp: In function ‘void readdata()’: user.cpp:20: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp:24: 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:33: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void solve()’: user.cpp:79: warning: comparison between signed and unsigned integer expressions