Compilare: user.cpp: In function ‘int main()’: user.cpp:17:15: warning: array subscript has type ‘char’ [-Wchar-subscripts] L[x[i]] = i; ^ user.cpp:21:19: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (L[x[i]] == i && !killed[x[i]]) { ^ user.cpp:21:41: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (L[x[i]] == i && !killed[x[i]]) { ^ user.cpp:24:51: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (x[j] == ch && !killed[x[j]]) { ^ user.cpp:27:34: warning: array subscript has type ‘char’ [-Wchar-subscripts] killed[ch] = 1; ^ user.cpp:10:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("calandrinon.in", "r", stdin); ^ user.cpp:11:44: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("calandrinon.out", "w", stdout); ^ user.cpp:14:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n", &n); ^ user.cpp:15:16: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(x + 1); ^ /tmp/ccfIChNy.o: In function `main': user.cpp:(.text.startup+0x6a): warning: the `gets' function is dangerous and should not be used.