Compilare: user.cpp: In function ‘int main()’: user.cpp:13:17: warning: unused variable ‘t’ [-Wunused-variable] int n,k,i,j,t,ans=0,x=1,l; ^ user.cpp:13:25: warning: unused variable ‘x’ [-Wunused-variable] int n,k,i,j,t,ans=0,x=1,l; ^ user.cpp:11:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("carry.in","r",stdin); ^ user.cpp:12:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("carry.out","w",stdout); ^ user.cpp:14:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d\n",&n,&k); ^ user.cpp:15:15: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(si+1); ^ /tmp/cccQUOgj.o: In function `main': user.cpp:(.text.startup+0x72): warning: the `gets' function is dangerous and should not be used.