#!/usr/bin/env python3
n, m = int(input()), 10**9+7
s = '( '+input()+' )'
s = s.replace('( ', 'f(').replace(' ', ',').replace('(', '([').replace(')', '])')
def times(l):
    a = 1
    for x in l: a = (a*x)%m
    return a

def f(l):
    l = [(x,x) if isinstance(x, int) else x for x in l]
    x = sum([x[1] for x in l])%m, times([x[0] for x in l])%m
    #print(x)
    return x
print(eval(s)[0])