Compilare: user.cpp: In function ‘int main()’: user.cpp:9:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("pufu.in","r",stdin); ^ user.cpp:10:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("pufu.out","w",stdout); ^ user.cpp:11:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&t); ^ user.cpp:14:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n",&n); w[1]=0; w[2]=0; w[3]=0; ^ user.cpp:17:22: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s+1); ^ /tmp/ccanFFYH.o: In function `main': user.cpp:(.text.startup+0xe9): warning: the `gets' function is dangerous and should not be used.