Compilare: user.cpp: In function ‘void dfs(int, int)’: user.cpp:21:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < g[a].size(); i++) ^ user.cpp: At global scope: user.cpp:2:15: warning: suggest parentheses around ‘-’ inside ‘<<’ [-Wparentheses] #define BUFS 1<<17 ^ user.cpp:53:10: note: in expansion of macro ‘BUFS’ int pz = BUFS - 1; ^ user.cpp: In function ‘void nxt()’: user.cpp:61:43: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buf, 1, BUFS, stdin), pz = 0; ^