Compilare: user.cpp: In function ‘int main()’: user.cpp:59:40: warning: operation on ‘k’ may be undefined [-Wsequence-point] b[++k] = make_pair(b[k+1].first, 2); ^ user.cpp:62:44: warning: operation on ‘k’ may be undefined [-Wsequence-point] b[++k] = make_pair(b[k+1].first + 1, 1); ^ user.cpp:43:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("patrate6.in","r",stdin); ^ user.cpp:44:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("patrate6.out","w",stdout); ^ user.cpp:46:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:48:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &a[i]); ^