Compilare: user.cpp: In function ‘void read()’: user.cpp:29: warning: ignoring return value of ‘FILE* fopen(const char*, const char*)’, declared with attribute warn_unused_result user.cpp:30: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp:34: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void solve()’: user.cpp:71: warning: comparison between signed and unsigned integer expressions user.cpp:87: warning: comparison between signed and unsigned integer expressions user.cpp:103: warning: comparison between signed and unsigned integer expressions user.cpp:67: warning: ignoring return value of ‘FILE* fopen(const char*, const char*)’, declared with attribute warn_unused_result user.cpp: In function ‘void read()’: user.cpp:30: warning: ‘f’ is used uninitialized in this function user.cpp: In function ‘void solve()’: user.cpp:66: warning: ‘g’ may be used uninitialized in this function