Compilare: user.cpp: In function ‘int main()’: user.cpp:66:31: warning: right operand of comma operator has no effect [-Wunused-value] x = b[n - i + 2], v[16], k = 0; ^ user.cpp:91:18: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] st[++nn] = NULL; ^ 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 ("patrate5.in", "r", stdin); ^ user.cpp:35:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("patrate5.out", "w", stdout); ^ user.cpp:38:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d", &n, &p); ^