import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

N = int(readline())
m = map(int,read().split())
CD = zip(m,m)

x = sum((c+1)//2 * d for c,d in CD)
x %= 10**9 + 7
print(x)