Compilare: user.cpp: In function ‘int go(int)’: user.cpp:18:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (; last < strlen(s); ++last) { ^ user.cpp: In function ‘int main()’: user.cpp:35:28: warning: format ‘%s’ expects argument of type ‘char*’, but argument 3 has type ‘char (*)[500005]’ [-Wformat=] scanf ("%d\n%s", &n, &s); ^ user.cpp:33:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("string.in", "r", stdin); ^ user.cpp:34:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("string.out", "w", stdout); ^ user.cpp:35:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d\n%s", &n, &s); ^