Compilare: user.cpp: In function ‘int main()’: user.cpp:14:19: warning: unused variable ‘x3’ [-Wunused-variable] int x1,x2,x3,x4; ^ user.cpp:14:22: warning: unused variable ‘x4’ [-Wunused-variable] int x1,x2,x3,x4; ^ user.cpp:7:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("marmote.in","r",stdin); ^ user.cpp:8:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("marmote.out","w",stdout); ^ user.cpp:10:37: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d",&n,&m,&k,&l); ^ user.cpp:13:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&a1,&a2); ^