class memory_alloc:
    def __init__(self,size):
        self.ChunkSize = 16
        self.MemSize = size
        self.NChunks = self.MemSize / self.ChunkSize
        self.freemap=[]
        for i in range(self.NChunks):
            self.freemap.append(0)
    
    def __str__(self):
        res=""
        for i in range(self.NChunks):
            if self.freemap[i]:
                res=res+chr(self.freemap[i])
            else:
                res=res+"."
        return res
    
    def allocate(self,n,flag):
        for i in range(self.NChunks):
            if self.freemap[i]==0:
                c = n-1; j=i+1; ok=1
                while (c>0) & (ok==1):
                    if j>=self.NChunks:
                        ok=0; break
                    if self.freemap[j]>0: ok=0
                    j = j+1
                    c = c-1
                if ok==1:
                    #print "allocate(%d)->%d" % (n,i)
                    for j in range(i,i+n):
                        self.freemap[j]=ord(flag)
                    return i
        #print "allocate(%d) fails for %s" % (n,c)
        return -1
    
    def free(self,a,n):
        for i in range(a,a+n):
            self.freemap[i]=0
        return