n,t=map(int,input().split())
a=[]
b=[]
c=[]
for i in range(1,n+1):
    aaa,bbb=map(int,input().split())
    a.append(aaa)
    b.append(bbb)
    c.append(0)
for i in range(0,n):
    if b[i]>=t:
        c[i]=0
    else:
        c[i]=a[i]*(t-b[i])
x,xi=0,0
for i in range(0,n):
    if x<c[i]:
        x=c[i]
        xi=i+1
    elif x==c[i] and xi>i:
        x=c[i]
        xi=i+1
print(xi)