Compilare: user.cpp: In function ‘int main()’: user.cpp:24:93: warning: array subscript has type ‘char’ [-Wchar-subscripts] if( vf < 1 || stack[vf] == ')' || s[i] == '(' ) { stack[++vf] = s[i]; ++frecv[ s[i] ]; } ^ user.cpp:25:35: warning: array subscript has type ‘char’ [-Wchar-subscripts] else --frecv[ stack[vf--] ]; ^ user.cpp:11:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("par.in","r",stdin); ^ user.cpp:12:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("par.out","w",stdout); ^ user.cpp:16:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n",&N); ^ user.cpp:17:28: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(s, NMax-1, stdin); ^