Compilare: user.cpp: In function ‘int main()’: user.cpp:39:11: warning: unused variable ‘j’ [-Wunused-variable] int n,m,i,j,a,b,cate=0,cost=0,k=0; ^ user.cpp:37:29: 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:38:31: 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:41:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&m); ^ user.cpp:44:51: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d",&(v[i].a),&(v[i].b),&(v[i].c) ); ^