Buggy python submission (verdict: Runtime Error):
import math
N,D,A=map(int,input().split())
l=[]
for i in range(N):
  k=tuple(map(int,input().split()))
  l.append(k)
l.sort(key=itemgetter(0))
S=[0]*N
ma=[0]*N
tmp=N-1
for i in reversed(range(N)):
  x=l[i][0]
  for j in reversed(range(0,tmp)):
    if abs(l[j][0]-(x-D))>D:
      ma[i]=j+1
      tmp=j+1
      break
  else:
    ma[i]=0
    tmp=0
ans=0
S[0]=math.ceil(l[0][1]/A)
for i in range(1,N):
  h=l[i][1]
  left=S[ma[i]-1] if ma[i]>0 else 0
  right=S[i-1]
  sum_=(right-left)*A
  if h<=sum_:
    S[i]=S[i-1]
    continue
  time=math.ceil((h-sum_)/A)
  S[i]=time+S[i-1]
print(S[N-1])

Fixed submission:
import math
N,D,A=map(int,input().split())
l=[]
for i in range(N):
  k=list(map(int,input().split()))
  l.append(k)
l.sort()
S=[0]*N
ma=[0]*N
tmp=N-1
for i in reversed(range(N)):
  x=l[i][0]
  for j in reversed(range(0,tmp)):
    if abs(l[j][0]-(x-D))>D:
      ma[i]=j+1
      tmp=j+1
      break
  else:
    ma[i]=0
    tmp=0
ans=0
S[0]=math.ceil(l[0][1]/A)
for i in range(1,N):
  h=l[i][1]
  left=S[ma[i]-1] if ma[i]>0 else 0
  right=S[i-1]
  sum_=(right-left)*A
  if h<=sum_:
    S[i]=S[i-1]
    continue
  time=math.ceil((h-sum_)/A)
  S[i]=time+S[i-1]
print(S[N-1])

Buggy python submission (verdict: Runtime Error):
import math
N,D,A=map(int,input().split())
l=[]
for i in range(N):
  x,h=map(int,input().split())
  l.append((x<<30)+h)
l.sort()
S=[0]*N
ma=[0]*N
tmp=N-1
for i in reversed(range(N)):
  x=l[i]>>30
  for j in reversed(range(0,tmp)):
    if abs(l[j]>>30-(x-D))>D:
      ma[i]=j+1
      tmp=j+1
      break
  else:
    ma[i]=0
    tmp=0
ans=0
S[0]=math.ceil(l[0]&(2**30-1)/A)
for i in range(1,N):
  h=l[i]&(2**30-1)
  left=S[ma[i]-1] if ma[i]>0 else 0
  right=S[i-1]
  sum_=(right-left)*A
  if h<=sum_:
    S[i]=S[i-1]
    continue
  time=math.ceil((h-sum_)/A)
  S[i]=time+S[i-1]
print(S[N-1])


Fixed submission:
import math
N,D,A=map(int,input().split())
l=[]
for i in range(N):
  k=list(map(int,input().split()))
  l.append(k)
l.sort()
S=[0]*N
ma=[0]*N
tmp=N-1
for i in reversed(range(N)):
  x=l[i][0]
  for j in reversed(range(0,tmp)):
    if abs(l[j][0]-(x-D))>D:
      ma[i]=j+1
      tmp=j+1
      break
  else:
    ma[i]=0
    tmp=0
ans=0
S[0]=math.ceil(l[0][1]/A)
for i in range(1,N):
  h=l[i][1]
  left=S[ma[i]-1] if ma[i]>0 else 0
  right=S[i-1]
  sum_=(right-left)*A
  if h<=sum_:
    S[i]=S[i-1]
    continue
  time=math.ceil((h-sum_)/A)
  S[i]=time+S[i-1]
print(S[N-1])

Buggy python submission (verdict: Time Limit Exceeded):
import math
N,D,A=map(int,input().split())
l=[]
for i in range(N):
  k=list(map(int,input().split()))
  l.append(k)
l.sort()
ma=[0]*N
tmp=1
for i in range(N):
  x=l[i][0]
  h=l[i][1]
  tmp=max(tmp,i+1)
  for j in range(tmp,N):
    if abs(l[j][0]-(x+D))>D:
      ma[i]=j
      tmp=j
      break
  else:
    ma[i]=N
    tmp=N
ans=0
for i in range(N):
  h=l[i][1]
  if h<=0:continue
  d=l[i][0]+D
  time=math.ceil(h/A)
  for j in range(i,ma[i]):
    l[j][1]-=time*A
  ans+=time
print(ans)

Fixed submission:
import math
N,D,A=map(int,input().split())
l=[]
for i in range(N):
  k=list(map(int,input().split()))
  l.append(k)
l.sort()
S=[0]*N
ma=[0]*N
tmp=N-1
for i in reversed(range(N)):
  x=l[i][0]
  for j in reversed(range(0,tmp)):
    if abs(l[j][0]-(x-D))>D:
      ma[i]=j+1
      tmp=j+1
      break
  else:
    ma[i]=0
    tmp=0
ans=0
S[0]=math.ceil(l[0][1]/A)
for i in range(1,N):
  h=l[i][1]
  left=S[ma[i]-1] if ma[i]>0 else 0
  right=S[i-1]
  sum_=(right-left)*A
  if h<=sum_:
    S[i]=S[i-1]
    continue
  time=math.ceil((h-sum_)/A)
  S[i]=time+S[i-1]
print(S[N-1])

Buggy python submission (verdict: Time Limit Exceeded):
import math
N,D,A=map(int,input().split())
l=[]
for i in range(N):
  k=list(map(int,input().split()))
  l.append(k)
l.sort()
ans=0
for i in range(N):
  h=l[i][1]
  if h<=0:continue
  d=l[i][0]+D
  time=math.ceil(h/A)
  s=set()
  for j in range(i,N):
    if abs(d-l[j][0])<=D:
      s.add(j)
    else:break
  for k in s:
    l[k][1]-=time*A
  ans+=time
print(ans)

Fixed submission:
import math
N,D,A=map(int,input().split())
l=[]
for i in range(N):
  k=list(map(int,input().split()))
  l.append(k)
l.sort()
S=[0]*N
ma=[0]*N
tmp=N-1
for i in reversed(range(N)):
  x=l[i][0]
  for j in reversed(range(0,tmp)):
    if abs(l[j][0]-(x-D))>D:
      ma[i]=j+1
      tmp=j+1
      break
  else:
    ma[i]=0
    tmp=0
ans=0
S[0]=math.ceil(l[0][1]/A)
for i in range(1,N):
  h=l[i][1]
  left=S[ma[i]-1] if ma[i]>0 else 0
  right=S[i-1]
  sum_=(right-left)*A
  if h<=sum_:
    S[i]=S[i-1]
    continue
  time=math.ceil((h-sum_)/A)
  S[i]=time+S[i-1]
print(S[N-1])

Buggy python submission (verdict: Runtime Error):
import math
N,D,A=map(int,input().split())
l=[]
for i in range(N):
  k=list(map(int,input().split()))
  l.append(k)
l.sort()
ans=0
for i in range(N):
  h=l[i][1]
  if h<=0:continue
  d=l[i][0]+D
  time=math.ceil(h/A)
  s=set()
  for j in range(i,n):
    if abs(d-l[j][0])<=D:
      s.add(j)
    else:break
  for k in s:
    l[k][1]-=time*A
  ans+=time
print(ans)
  	


Fixed submission:
import math
N,D,A=map(int,input().split())
l=[]
for i in range(N):
  k=list(map(int,input().split()))
  l.append(k)
l.sort()
S=[0]*N
ma=[0]*N
tmp=N-1
for i in reversed(range(N)):
  x=l[i][0]
  for j in reversed(range(0,tmp)):
    if abs(l[j][0]-(x-D))>D:
      ma[i]=j+1
      tmp=j+1
      break
  else:
    ma[i]=0
    tmp=0
ans=0
S[0]=math.ceil(l[0][1]/A)
for i in range(1,N):
  h=l[i][1]
  left=S[ma[i]-1] if ma[i]>0 else 0
  right=S[i-1]
  sum_=(right-left)*A
  if h<=sum_:
    S[i]=S[i-1]
    continue
  time=math.ceil((h-sum_)/A)
  S[i]=time+S[i-1]
print(S[N-1])

Buggy python submission (verdict: Runtime Error):
import math
N,D,A=map(int,input().split())
l=[]
for i in range(N):
  k=list(map(int,input().split()))
  l.append(k)
l=l.sort()
ans=0
for i in range(N):
  h=l[i][1]
  if h<=0:continue
  d=l[i][0]+D
  time=math.ceil(h/A)
  s=set()
  for j in range(i,n):
    if abs(d-l[j][0])<=D:
      s.add(j)
    else:break
  for k in s:
    l[k][1]-=time*A
  ans+=time
print(ans)
  	

Fixed submission:
import math
N,D,A=map(int,input().split())
l=[]
for i in range(N):
  k=list(map(int,input().split()))
  l.append(k)
l.sort()
S=[0]*N
ma=[0]*N
tmp=N-1
for i in reversed(range(N)):
  x=l[i][0]
  for j in reversed(range(0,tmp)):
    if abs(l[j][0]-(x-D))>D:
      ma[i]=j+1
      tmp=j+1
      break
  else:
    ma[i]=0
    tmp=0
ans=0
S[0]=math.ceil(l[0][1]/A)
for i in range(1,N):
  h=l[i][1]
  left=S[ma[i]-1] if ma[i]>0 else 0
  right=S[i-1]
  sum_=(right-left)*A
  if h<=sum_:
    S[i]=S[i-1]
    continue
  time=math.ceil((h-sum_)/A)
  S[i]=time+S[i-1]
print(S[N-1])