Compilare: user.cpp: In function ‘int dfs(int, bool*)’: user.cpp:28:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<v[node].size(); i++) ~^~~~~~~~~~~~~~~ user.cpp: In function ‘void remove_edge(int, int)’: user.cpp:35:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<v[node].size(); i++) ~^~~~~~~~~~~~~~~ user.cpp:41:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<v[node2].size(); i++) ~^~~~~~~~~~~~~~~~ user.cpp: In function ‘void add_edge(int, int)’: user.cpp:50:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<v[node].size(); i++) ~^~~~~~~~~~~~~~~ user.cpp:56:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<v[node2].size(); i++) ~^~~~~~~~~~~~~~~~ user.cpp: In function ‘int valid(int, int)’: user.cpp:66:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<v[node].size(); i++) ~^~~~~~~~~~~~~~~ user.cpp: In function ‘void euler(int)’: user.cpp:86:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<v[node].size(); i++) ~^~~~~~~~~~~~~~~ user.cpp:85:9: warning: unused variable ‘ok’ [-Wunused-variable] int ok=1; ^~ user.cpp: In function ‘void read()’: user.cpp:14:28: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d %d",&n,&m); ^ user.cpp:17:32: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d %d",&x,&y); ^