Задание 27 #08

N, t = int(input()), int(input()) 
a = [] 
b = [] 
for i in range(N): 
    ai, bi = map(int, input().split()) 
    a.append(ai) 
    b.append(bi) 

br = 0 
for j in range(N): 
    br += b[j] 
ar = 0 
res = br + t 
for i in range(N): 
    br -= b[i] 
    ar += a[i] 
    if ar + br + t < res: 
        res = ar + br + t 
print(res)

n = int(input()) 
road = int(input()) 
a = 0 
b = road 
for i in range(n): 
    ai, bi = list(map(int, input().split())) 
    a += ai 
    b = min(b+bi, a+road) 
print(b)