605B - Lazy Student - CodeForces Solution

n,m=map(int,input().split())
inc=[0]*m
edges=[]
for i in range(m):
    a,b=map(int,input().split())
    inc[i]=b
    edges.append((a,b,i))
edges.sort(key=lambda x:(x[0],-x[1]))
ans=[[] for _ in range(m)]
last=1
fro=2
to=3
f=True
for a,b,ind in edges:
    if inc[ind]:
        last+=1
        ans[ind]=[1,last]
    else:
        if to==fro:
            to+=1
            fro=2
        if to>last:
            f=False
            break
        ans[ind]=[fro,to]
        fro+=1
if f:
    for el in ans:
        print(*el)
else:
    print(-1)