Compilare: user.cpp: In function ‘int main()’: user.cpp:62:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("lazy.in","r",stdin); ^ user.cpp:63:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("lazy.out","w",stdout); ^ user.cpp:64:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&N,&M); ^ user.cpp:65:102: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for (i=1;i<=M;i++) scanf("%d %d %lld %lld",&X[i],&Y[i],&efort[i],&cost[i]),ind[i]=TT[i]=i,RG[i]=1; ^