Compilare: user.cpp:2:82: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type] short x[4]={-1,0,1,0},l[1<<15],c[1<<15],a[177][177],b,d,o,q,n,m,k,i,j,v,p,u;main(){std::ifstream f("alee.in");f>>n>>m;while(m--)f>>i>>k,a[i][k]=-1;f>>b>>d>>o>>q;for(i=0;i++<n;)a[i][0]=a[i][n+1]=a[0][i]=a[n+1][i]=-1;for(a[b][d]=1,l[p]=b,c[p]=d;p<=u&&!a[o][q];)for(j=l[p],v=c[p++],k=-1;k++<3;)if(!a[j+x[k]][v+x[3-k]])a[j+x[k]][v+x[3-k]]=a[j][v]+1,l[++u]=j+x[k],c[u]=v+x[3-k];std::ofstream("alee.out")<<a[o][q];} ^