Compilare: user.cpp: In function ‘int main()’: user.cpp:2:92: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] using namespace std;bitset <32> b;char s[5000010];int main(){freopen("subbit.in","r",stdin);freopen("subbit.out","w",stdout);int nrb=1,wb=1,nr=0,used=0;gets(s);for(int x=0;s[x];x++){s[x]-='0';do{wb--;if(wb==-1){used+=nrb;nr++;b=nr;if(nr>1&&b.count()==1)nrb++;wb=nrb-1;}}while(b[wb]!=s[x]);}printf("%d",used+nrb-wb);return 0;} ^ user.cpp:2:125: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] using namespace std;bitset <32> b;char s[5000010];int main(){freopen("subbit.in","r",stdin);freopen("subbit.out","w",stdout);int nrb=1,wb=1,nr=0,used=0;gets(s);for(int x=0;s[x];x++){s[x]-='0';do{wb--;if(wb==-1){used+=nrb;nr++;b=nr;if(nr>1&&b.count()==1)nrb++;wb=nrb-1;}}while(b[wb]!=s[x]);}printf("%d",used+nrb-wb);return 0;} ^ user.cpp:2:160: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] using namespace std;bitset <32> b;char s[5000010];int main(){freopen("subbit.in","r",stdin);freopen("subbit.out","w",stdout);int nrb=1,wb=1,nr=0,used=0;gets(s);for(int x=0;s[x];x++){s[x]-='0';do{wb--;if(wb==-1){used+=nrb;nr++;b=nr;if(nr>1&&b.count()==1)nrb++;wb=nrb-1;}}while(b[wb]!=s[x]);}printf("%d",used+nrb-wb);return 0;} ^ /tmp/ccOJq0o8.o: In function `main': user.cpp:(.text.startup+0x56): warning: the `gets' function is dangerous and should not be used.