Compilare: user.cpp: In function ‘void read()’: user.cpp:22:13: warning: unused variable ‘x’ [-Wunused-variable] int x, y; ^ user.cpp:22:16: warning: unused variable ‘y’ [-Wunused-variable] int x, y; ^ user.cpp: In function ‘void init()’: user.cpp:31:47: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = 0; j < v[x = edge[i].s].size(); ++ j) ^ user.cpp: In function ‘void read()’: user.cpp:18:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("tester.in", "r", stdin); ^ user.cpp:19:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &m); ^ user.cpp:23:47: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &edge[i].f, &edge[i].s); ^ user.cpp: In function ‘void write()’: user.cpp:84:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("tester.out", "w", stdout); ^