549 B | 549 chars
import sys
from math import sqrt, pi, sin, factorial
inp = lambda : sys.stdin.readline()[:-1].strip()
mii = lambda x = " " : [*map(int,inp().split(x))]
mfi = lambda x = " " : [*map(float,inp().split(x))]
ii = lambda : int(inp())
fi = lambda : float(inp())
p = print
def solve():
n, q = mii()
l = [0] + [ii() for _ in range(n)]
d = [0]
for i in range(1, n + 1):
d.append(d[i - 1] + l[i])
for _ in range(q):
a, b = mii()
print(d[b] - d[a - 1])
if __name__ == "__main__":
tc = 1
for t in range(1, tc+1):
ret = solve()