Compilare: user.cpp: In function ‘void Solve()’: user.cpp:14:15: warning: NULL used in arithmetic [-Wpointer-arith] while(c[i]!=NULL) ^ user.cpp:15:16: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] {if(c[i]>='a'&&c[i]<='z'||c[i]>='A'&&c[i]<='Z') ^ user.cpp:16:25: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] {s[n++]=c[i]; s[n]=NULL;} ^