Compilare: user.cpp: In function ‘int main()’: user.cpp:128:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < Ans.size(); ++ i) ^ user.cpp:90:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("text5.in", "r", stdin); ^ user.cpp:91:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("text5.out", "w", stdout); ^ user.cpp:93:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i\n", &N); ^ user.cpp:94:16: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(S + 1); ^ /tmp/ccKyrAxO.o: In function `main': user.cpp:(.text.startup+0x6a): warning: the `gets' function is dangerous and should not be used.