Compilare: user.cpp: In function ‘int main()’: user.cpp:25:40: warning: array subscript has type ‘char’ [-Wchar-subscripts] for (int i = 1;i <= n;++i) ++r[a[i]],--r[b[i]]; ^ user.cpp:25:50: warning: array subscript has type ‘char’ [-Wchar-subscripts] for (int i = 1;i <= n;++i) ++r[a[i]],--r[b[i]]; ^ user.cpp:29:15: warning: array subscript has type ‘char’ [-Wchar-subscripts] v[b[i]].push(i); ^ user.cpp:33:30: warning: array subscript has type ‘char’ [-Wchar-subscripts] p[i] = n - v[a[i]].front() + 1;v[a[i]].pop(); ^ user.cpp:33:50: warning: array subscript has type ‘char’ [-Wchar-subscripts] p[i] = n - v[a[i]].front() + 1;v[a[i]].pop(); ^ user.cpp:20:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("swap.in","r",stdin); ^ user.cpp:21:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("swap.out","w",stdout); ^ user.cpp:22:14: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(a+1);gets(b+1); ^ user.cpp:22:24: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(a+1);gets(b+1); ^ /tmp/ccNh6SaI.o: In function `main': user.cpp:(.text.startup+0x56): warning: the `gets' function is dangerous and should not be used.