Buggy python submission (verdict: Runtime Error):
N,M = map(int,input().split())
A,B = [],[]
for i in range(N):
    A_next, B_next = map(int,input().split())
    A.append(A_next)
    B.append(B_next)
shop = list(zip(A,B))
shop.sort(key=lambda x:x[0])
def count(i,M):
    if(M==0):
        return 0
    elif(shop[i][1]<=M):
        return count(i+1,M-shop[i][1])+shop[i][0]*shop[i][1]
    else:
        return M*shop[i][0]
a = count(0,M)
print(a)

Fixed submission:
N,M = map(int, input().split())
A,B = [],[]
for i in range(N):
    A_next, B_next = map(int,input().split())
    A.append(A_next)
    B.append(B_next)
l = sorted(list(zip(A,B)), key=lambda x:x[0])
count = 0
value = 0
i = 0
while(count<M):
    if(M-count<l[i][1]):
        value = value + l[i][0]*(M-count)
        break
    else:
        value = value + l[i][0]*l[i][1]
        count = count + l[i][1]
        i = i + 1
print(value)

Buggy python submission (verdict: Runtime Error):
N,M = map(int,input().split())
A,B = [],[]
for i in range(N):
    A_next, B_next = map(int,input().split())
    A.append(A_next),B.append(B_next)
shop = list(zip(A,B))
shop.sort(key=lambda x:x[0])
def count(i,M):
    if(M==0):
        return 0
    elif(shop[i][1]<=M):
        return count(i+1,M-shop[i][1])+shop[i][0]*shop[i][1]
    else:
        return M*shop[i][0]
a = count(0,M)
print(a)

Fixed submission:
N,M = map(int, input().split())
A,B = [],[]
for i in range(N):
    A_next, B_next = map(int,input().split())
    A.append(A_next)
    B.append(B_next)
l = sorted(list(zip(A,B)), key=lambda x:x[0])
count = 0
value = 0
i = 0
while(count<M):
    if(M-count<l[i][1]):
        value = value + l[i][0]*(M-count)
        break
    else:
        value = value + l[i][0]*l[i][1]
        count = count + l[i][1]
        i = i + 1
print(value)

Buggy python submission (verdict: Runtime Error):
N,M = map(int,input().split())
A,B = [],[]
for i in range(N):
    A_next, B_next = map(int,input().split())
    A.append(A_next),B.append(B_next)
shop = list(zip(A,B))
shop.sort(key=lambda x:x[0])
def count(i,M):
    if(M==0):
        return 0
    elif(shop[i][1]<=M):
        return count(i+1,M-shop[i][1])+shop[i][0]*shop[i][1]
    else:
        return M*shop[i][0]
count(0,M)

Fixed submission:
N,M = map(int, input().split())
A,B = [],[]
for i in range(N):
    A_next, B_next = map(int,input().split())
    A.append(A_next)
    B.append(B_next)
l = sorted(list(zip(A,B)), key=lambda x:x[0])
count = 0
value = 0
i = 0
while(count<M):
    if(M-count<l[i][1]):
        value = value + l[i][0]*(M-count)
        break
    else:
        value = value + l[i][0]*l[i][1]
        count = count + l[i][1]
        i = i + 1
print(value)

Buggy python submission (verdict: Runtime Error):
N,M = map(int,input().split())
A,B = [],[]
for i in range(N):
    A_next, B_next = map(int,input().split())
    A.append(A_next),B.append(B_next)
shop = list(zip(A,B))
shop.sort(key=lambda x:x[0])
def count(i,M):
    if(M==0):
        return 0
    elif(shop[i][1]<=M):
        return count(i+1,M-shop[i][1])+shop[i][0]*shop[i][1]
    else:
        return M*shop[i][0]
count(0,M)

Fixed submission:
N,M = map(int, input().split())
A,B = [],[]
for i in range(N):
    A_next, B_next = map(int,input().split())
    A.append(A_next)
    B.append(B_next)
l = sorted(list(zip(A,B)), key=lambda x:x[0])
count = 0
value = 0
i = 0
while(count<M):
    if(M-count<l[i][1]):
        value = value + l[i][0]*(M-count)
        break
    else:
        value = value + l[i][0]*l[i][1]
        count = count + l[i][1]
        i = i + 1
print(value)