Compilare: user.cpp: In function ‘void unionn(int, int)’: user.cpp:25:7: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if(a!=b) ^ user.cpp: In function ‘int main()’: user.cpp:33:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("apm.in","r",stdin); ^ user.cpp:34:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("apm.out","w",stdout); ^ user.cpp:36:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&m); ^ user.cpp:38:51: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d",&v[i].x,&v[i].y,&v[i].cost); ^