Compilare: user.cpp: In function ‘int main()’: user.cpp:31:38: warning: suggest parentheses around ‘-’ in operand of ‘&’ [-Wparentheses] ok[i & 1][j + 1] = (ok[1 - i & 1][j + 2] && str[j + 1] == str[i]); ^ user.cpp:13:15: warning: unused variable ‘len’ [-Wunused-variable] int i, n, len, j; ^ user.cpp:16:30: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fi,"%s " ,str + 1); ^