Compilare: main.cpp: In function 'int main()': main.cpp:15:9: warning: unused variable 'u' [-Wunused-variable] int n,i,u=0; ^ main.cpp:13:29: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("chei.in","r",stdin); ^ main.cpp:14:31: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("chei.out","w",stdout); ^ main.cpp:16:25: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fgets(ch+1,100003,stdin); ^