Compilare: user.cpp: In function ‘int reunite(int, int)’: user.cpp:39:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:107:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<a[x].size(); ++i) ^ user.cpp:111:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<a[y].size(); ++i) ^ user.cpp:67:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("online.in", "rt", stdin); ^ user.cpp:68:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("online.out", "wt", stdout); ^ user.cpp:70:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ user.cpp:73:56: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &edge[i].x, &edge[i].y, &edge[i].c); ^ user.cpp:93:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &k); ^ user.cpp:97:36: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &x, &y, &c); ^