Compilare: user.cpp: In function ‘int main()’: user.cpp:49:32: 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:50:34: 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:51:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&N,&M); ^ user.cpp:54:47: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d",&x[i],&y[i],&cost[i]); ^