Compilare: user.cpp: In function ‘int main()’: user.cpp:101:9: warning: unused variable ‘last’ [-Wunused-variable] int last = 0 ; ^ user.cpp:45:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen( IN , "r" , stdin ); ^ user.cpp:46:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen( OUT , "w" , stdout ); ^ user.cpp:47:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf( "%d%d", &n , &m ); ^ user.cpp:51:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&cost,&num); ^ user.cpp:53:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",v+j); ^