Compilare: user.cpp: In function ‘int main()’: user.cpp:11:28: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("cal.in","r",stdin); scanf("%d %d %d %d\n",&sx,&sy,&s,&n); ^ user.cpp:11:66: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] freopen("cal.in","r",stdin); scanf("%d %d %d %d\n",&sx,&sy,&s,&n); ^ user.cpp:15:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n",&x,&y); ^ user.cpp:18:30: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("cal.out","w",stdout); printf("%d",sol); fclose(stdout); ^