ll@N,@M,@A[N],t,f,r;
wt(bsearch_max[ll,t,0,1d10][r=0;f=1;rep(i,N){if(A[i]<t*M){if(r<t*M-A[i])f=0;else r-=t*M-A[i];}else r+=A[i]-t*M;}](f));