Compilare: user.cpp: In function ‘void pre()’: user.cpp:26: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void solve()’: user.cpp:40: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘int main()’: user.cpp:63: warning: comparison between signed and unsigned integer expressions