Compilare: main.cpp:2:18: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type] int t,n,i,j;main(){std::fstream a("bunicu.in");std::ofstream o("bunicu.out");a>>t;std::string v;for(;i<t;i++){a>>n;for(j=0;j<n;j++){a>>v;o<<!(v[j]-48);}o<<"\n";}} ^