Compilare: user.cpp: In function ‘void read()’: user.cpp:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:47: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void pairing(int)’: user.cpp:64: warning: comparison between signed and unsigned integer expressions user.cpp:74: warning: comparison between signed and unsigned integer expressions user.cpp:87: warning: comparison between signed and unsigned integer expressions user.cpp:90: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void dfs()’: user.cpp:143: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void write()’: user.cpp:207: warning: comparison between signed and unsigned integer expressions user.cpp:212: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:222: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result