Compilare: user.cpp: In function ‘int f(int, int)’: user.cpp:4:17: warning: suggest parentheses around arithmetic in operand of ‘|’ [-Wparentheses] return r+c?c&1|r*2&2|4*f(r/2,c/2):0; ^ user.cpp: In function ‘int main()’: user.cpp:9:28: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("z.in","r", stdin); ^ user.cpp:10:29: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("z.out","w",stdout); ^ user.cpp:11:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&N,&K); ^ user.cpp:14:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&x,&y);x--;y--; ^