Solution18

import sys
with open("input.txt", "r") as file:
    sys.stdin = file

    a = [ int(input()) for i in range(1000) ]
    k = 0
    for i in range(0, 1000):
        for j in range(0, 1000):
            if (j - i >= 11) and (a[i] + a[j] < 200):
                k += 1
    print(k)