Compilare: user.cpp: In function ‘void solve()’: user.cpp:9:12: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s); n=strlen(s); ^ user.cpp: In function ‘int main()’: user.cpp:20:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("alibaba.in","r",stdin); ^ user.cpp:21:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("alibaba.out","w",stdout); ^ user.cpp:22:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d\n", &n, &t); t=n-t; ^ /tmp/ccqWRMbU.o: In function `solve()': user.cpp:(.text+0x29): warning: the `gets' function is dangerous and should not be used.