Compilare: main.cpp: In function 'int main()': main.cpp:18:19: warning: suggest parentheses around comparison in operand of '^' [-Wparentheses] if(a^b^c^d==0) ~^~~ main.cpp:8:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("chocolate.in","r",stdin); ^ main.cpp:9:40: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("chocolate.out","w",stdout); ^ main.cpp:10:19: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&t); ^ main.cpp:13:38: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d",&n,&m,&x,&y); ^