Compilare: user.cpp: In function ‘int main()’: user.cpp:28:25: warning: format ‘%s’ expects argument of type ‘char*’, but argument 3 has type ‘char (*)[500010]’ [-Wformat=] scanf("%d\n%s",&n,&s); ^ user.cpp:31:9: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] s[0]=NULL; ^ user.cpp:25:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("string.in","r",stdin); ^ user.cpp:26:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("string.out","w",stdout); ^ user.cpp:28:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n%s",&n,&s); ^ user.cpp:47:24: warning: ‘sol’ may be used uninitialized in this function [-Wmaybe-uninitialized] if((sol&(1<<i))==0) ^