Compilare: user.cpp: In function 'void dfs(int)': user.cpp:24: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'int main()': user.cpp:86: warning: comparison between signed and unsigned integer expressions user.cpp:88: warning: comparison between signed and unsigned integer expressions user.cpp:32: warning: unused variable 'n' user.cpp:34: warning: unused variable 'j' user.cpp:34: warning: unused variable 'k' user.cpp:67: warning: 'y1' may be used uninitialized in this function user.cpp:83: warning: 'start' may be used uninitialized in this function