Compilare: user.cpp: In function ‘int solve(char*, int)’: user.cpp:42:14: warning: unused variable ‘c’ [-Wunused-variable] char c = s[mid]; ^ user.cpp: In function ‘int main()’: user.cpp:57:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hacker.in", "r", stdin); ^ user.cpp:58:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hacker.out", "w", stdout); ^ user.cpp:60:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &k); ^ user.cpp:62:26: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(s, MAXN, stdin); ^