Buggy python submission (verdict: Time Limit Exceeded):
import sys,math
sr = sys.stdin.readline
def I(i=0):return [int(x)-i for x in sr().split()]
L1,L2 = [],[]

N,D,A = I()
for i in range(N):
    X,H = I()
    L1.append([X,math.ceil(H/A)])
L1 = sorted(L1)
ans = 0
j = 1
L2 = [-1]*N
for i in range(N):
    lim = L1[i][0] + 2*D
    for k in range(j,N):
        if L1[k][0] > lim:
            L2[i] = k-1
            j = k-1
            break
        elif k == N-1:
            L2[i] = N-1
            j = N-1
for i in range(N):
    x,h = L1[i] 
    if h > 0:
        ans += h
        for j in range(i,L2[i]+1):
            L1[j][1] -= h
print(ans)

Fixed submission:
import sys,math
sr = sys.stdin.readline
def I(i=0):return [int(x)-i for x in sr().split()]
L1,L2 = [],[]

N,D,A = I()
for i in range(N):
    X,H = I()
    L1.append([X,math.ceil(H/A)])
L1 = sorted(L1)
j = 1
L2 = [-1]*N
for i in range(N):
    lim = L1[i][0] + 2*D
    for k in range(j,N):
        if L1[k][0] > lim:
            L2[i] = k-1
            j = k-1
            break
        elif k == N-1:
            L2[i] = N-1
            j = N-1
ans = 0
a,s = 0,0
for i in range(N):
    x,h = L1[i]
    h -= a
    if h > 0:
        ans += h
        a += h
        L1[i][1] = h
    else:
        L1[i][1] = 0
    while s < N and L2[s] <= i:
        a -= L1[s][1]
        s += 1
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
import sys,math
sr = sys.stdin.readline
def I(i=0):return [int(x)-i for x in sr().split()]
L1,L2 = [],[]

N,D,A = I()
for i in range(N):
    X,H = I()
    L1.append([X,math.ceil(H/A)])
L2 = sorted(L1)
ans = 0
for i in range(N):
    x,h = L2[i] 
    if h > 0:
        ans += h
        L2[i][1] = 0
        lim = x + 2*D
        for j in range(1,N-i):
            if L2[i+j][0] <= lim:
                L2[i+j][1] -= h
            else:
                break
print(ans)

Fixed submission:
import sys,math
sr = sys.stdin.readline
def I(i=0):return [int(x)-i for x in sr().split()]
L1,L2 = [],[]

N,D,A = I()
for i in range(N):
    X,H = I()
    L1.append([X,math.ceil(H/A)])
L1 = sorted(L1)
j = 1
L2 = [-1]*N
for i in range(N):
    lim = L1[i][0] + 2*D
    for k in range(j,N):
        if L1[k][0] > lim:
            L2[i] = k-1
            j = k-1
            break
        elif k == N-1:
            L2[i] = N-1
            j = N-1
ans = 0
a,s = 0,0
for i in range(N):
    x,h = L1[i]
    h -= a
    if h > 0:
        ans += h
        a += h
        L1[i][1] = h
    else:
        L1[i][1] = 0
    while s < N and L2[s] <= i:
        a -= L1[s][1]
        s += 1
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
import sys,math
sr = sys.stdin.readline
def I(i=0):return [int(x)-i for x in sr().split()]
L1,L2 = [],[]

N,D,A = I()
for i in range(N):
    X,H = I()
    L1.append([X,math.ceil(H/A)])
L2 = sorted(L1)
ans = 0
for i in range(N):
    x,h = L2[i] 
    if h > 0:
        ans += h
        L2[i][1] = 0
        lim = x + 2*D
        for j in range(1,N-i):
            if L2[i+j][0] <= lim:
                L2[i+j][1] -= h
            else:
                break
print(ans)

Fixed submission:
import sys,math
sr = sys.stdin.readline
def I(i=0):return [int(x)-i for x in sr().split()]
L1,L2 = [],[]

N,D,A = I()
for i in range(N):
    X,H = I()
    L1.append([X,math.ceil(H/A)])
L1 = sorted(L1)
j = 1
L2 = [-1]*N
for i in range(N):
    lim = L1[i][0] + 2*D
    for k in range(j,N):
        if L1[k][0] > lim:
            L2[i] = k-1
            j = k-1
            break
        elif k == N-1:
            L2[i] = N-1
            j = N-1
ans = 0
a,s = 0,0
for i in range(N):
    x,h = L1[i]
    h -= a
    if h > 0:
        ans += h
        a += h
        L1[i][1] = h
    else:
        L1[i][1] = 0
    while s < N and L2[s] <= i:
        a -= L1[s][1]
        s += 1
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
import sys,collections,math,random,fractions,bisect;sys.setrecursionlimit(10**7)
sr = sys.stdin.readline;
def I(i=0): t = [int(x)-i for x in sr().split()];return t
def S(): t = sr().split(); return t if len(t) > 1 else t[0]
L1,L2,L3,L4, = [],[],[],[]
 
N,D,A = I()
for i in range(N):
    X,H = I()
    L1.append([X,math.ceil(H/A)])
L2 = sorted(L1)
ans = 0
for i in range(N):
    if L2[i][1] > 0:
        ans += L2[i][1]
        lim = L2[i][0] + 2*D
        for j in range(1,N-i):
            if L2[i+j][0] <= lim:
                L2[i+j][1] -= L2[i][1]
            else:
                break
        L2[i][1] -= L2[i][1]
print(ans)

Fixed submission:
import sys,math
sr = sys.stdin.readline
def I(i=0):return [int(x)-i for x in sr().split()]
L1,L2 = [],[]

N,D,A = I()
for i in range(N):
    X,H = I()
    L1.append([X,math.ceil(H/A)])
L1 = sorted(L1)
j = 1
L2 = [-1]*N
for i in range(N):
    lim = L1[i][0] + 2*D
    for k in range(j,N):
        if L1[k][0] > lim:
            L2[i] = k-1
            j = k-1
            break
        elif k == N-1:
            L2[i] = N-1
            j = N-1
ans = 0
a,s = 0,0
for i in range(N):
    x,h = L1[i]
    h -= a
    if h > 0:
        ans += h
        a += h
        L1[i][1] = h
    else:
        L1[i][1] = 0
    while s < N and L2[s] <= i:
        a -= L1[s][1]
        s += 1
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
import sys,collections,math,random,fractions,bisect;sys.setrecursionlimit(10**7)
sr = sys.stdin.readline; P = print; P2 = lambda x: print(*x, sep="\n")
def I(i=0): t = [int(x)-i for x in sr().split()];return t
def S(): t = sr().split(); return t if len(t) > 1 else t[0]
L1,L2,L3,L4, = [],[],[],[]
 
N,D,A = I()
for i in range(N):
    X,H = I()
    L1.append([X,math.ceil(H/A)])
L2 = sorted(L1)
ans = 0
for i in range(N):
    if L2[i][1] > 0:
        ans += L2[i][1]
        lim = L2[i][0] + 2*D
        for j in range(1,N-i):
            if L2[i+j][0] <= lim:
                L2[i+j][1] -= L2[i][1]
            else:
                break
        L2[i][1] -= L2[i][1]
print(ans)

Fixed submission:
import sys,math
sr = sys.stdin.readline
def I(i=0):return [int(x)-i for x in sr().split()]
L1,L2 = [],[]

N,D,A = I()
for i in range(N):
    X,H = I()
    L1.append([X,math.ceil(H/A)])
L1 = sorted(L1)
j = 1
L2 = [-1]*N
for i in range(N):
    lim = L1[i][0] + 2*D
    for k in range(j,N):
        if L1[k][0] > lim:
            L2[i] = k-1
            j = k-1
            break
        elif k == N-1:
            L2[i] = N-1
            j = N-1
ans = 0
a,s = 0,0
for i in range(N):
    x,h = L1[i]
    h -= a
    if h > 0:
        ans += h
        a += h
        L1[i][1] = h
    else:
        L1[i][1] = 0
    while s < N and L2[s] <= i:
        a -= L1[s][1]
        s += 1
print(ans)

Buggy python submission (verdict: Runtime Error):
import sys,collections,math,random,fractions,bisect;sys.setrecursionlimit(10**7)
sr = sys.stdin.readline; P = print; P2 = lambda x: print(*x, sep="\n")
def I(i=0): t = [int(x)-i for x in sr().split()];return t 
def S(): t = sr().split(); return t if len(t) > 1 else t[0]
L1,L2,L3,L4, = [],[],[],[]

H,N = I()
for i in range(N):
    A,B = I()
    L1.append([A,B,A/B])
L2 = sorted(L1,reverse=True,key=lambda x: x[2])
ans = 0
for i in range(10):
    for e in L2:
        if H >= e[0]:
            ans += H//e[0] * e[1]
            H = H%e[0]
            print(ans,H)
            break
print(ans,H)
L3 = sorted(L1,key=lambda x: x[1])
P2(L3)
if H > 0:
    for e in L3:
        if H <= e[0]:
            ans += e[1]
            break
print(ans,H)

Fixed submission:
import sys,math
sr = sys.stdin.readline
def I(i=0):return [int(x)-i for x in sr().split()]
L1,L2 = [],[]

N,D,A = I()
for i in range(N):
    X,H = I()
    L1.append([X,math.ceil(H/A)])
L1 = sorted(L1)
j = 1
L2 = [-1]*N
for i in range(N):
    lim = L1[i][0] + 2*D
    for k in range(j,N):
        if L1[k][0] > lim:
            L2[i] = k-1
            j = k-1
            break
        elif k == N-1:
            L2[i] = N-1
            j = N-1
ans = 0
a,s = 0,0
for i in range(N):
    x,h = L1[i]
    h -= a
    if h > 0:
        ans += h
        a += h
        L1[i][1] = h
    else:
        L1[i][1] = 0
    while s < N and L2[s] <= i:
        a -= L1[s][1]
        s += 1
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
import sys,collections,math,random,fractions,bisect;sys.setrecursionlimit(10**7)
sr = sys.stdin.readline; P = print; P2 = lambda x: print(*x, sep="\n")
def I(i=0): t = [int(x)-i for x in sr().split()];return t
def S(): t = sr().split(); return t if len(t) > 1 else t[0]
L1,L2,L3,L4, = [],[],[],[]
 
N,D,A = I()
for i in range(N):
    X,H = I()
    L1.append([X,math.ceil(H/A)])
L2 = sorted(L1)
ans = 0
for i in range(N):
    if L2[i][1] > 0:
        ans += L2[i][1]
        lim = L2[i][0] + 2*D
        for j in range(1,N-i):
            if L2[i+j][0] <= lim:
                L2[i+j][1] -= L2[i][1]
            else:
                break
        L2[i][1] -= L2[i][1]
print(ans)

Fixed submission:
import sys,math
sr = sys.stdin.readline
def I(i=0):return [int(x)-i for x in sr().split()]
L1,L2 = [],[]

N,D,A = I()
for i in range(N):
    X,H = I()
    L1.append([X,math.ceil(H/A)])
L1 = sorted(L1)
j = 1
L2 = [-1]*N
for i in range(N):
    lim = L1[i][0] + 2*D
    for k in range(j,N):
        if L1[k][0] > lim:
            L2[i] = k-1
            j = k-1
            break
        elif k == N-1:
            L2[i] = N-1
            j = N-1
ans = 0
a,s = 0,0
for i in range(N):
    x,h = L1[i]
    h -= a
    if h > 0:
        ans += h
        a += h
        L1[i][1] = h
    else:
        L1[i][1] = 0
    while s < N and L2[s] <= i:
        a -= L1[s][1]
        s += 1
print(ans)