Compilare: user.cpp: In function ‘int main()’: user.cpp:33:21: warning: unused variable ‘k’ [-Wunused-variable] int N,i,j,M,x,y,k; ^ user.cpp:31:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("arbint.in","r",stdin); ^ user.cpp:32:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("arbint.out","w",stdout); ^ user.cpp:34:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&N,&M); ^ user.cpp:37:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&x); ^ user.cpp:42:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d",&j,&x,&y); ^