Buggy python submission (verdict: Runtime Error):
import sys
import math
import functools
stdin = sys.stdin
mod = 10**9 + 7

ns = lambda: stdin.readline().rstrip()
ni = lambda: int(ns())
na = lambda: list(map(int, stdin.readline().split()))
sa = lambda h: [list(map(int, stdin.readline().split())) for i in range(h)]

h, n = na()
a, b = [], []
for _ in range(n):
    ai, bi = na()
    a.append(ai)
    b.append(bi)
inf = 10**9
dp = [[inf]* (10**3+1) for _ in range(n+1)]
for i in range(n):
    for j in range(1, 10**3+1):
        if j < a[i]:
            dp[i+1][j] = min(dp[i][j],((j-1)//a[i]+1)*b[i])
        else:
            dp[i+1][j] = min(dp[i][j],((j-1)//a[i]+1)*b[i], dp[i+1][j - a[i]] + b[i])
print(dp[n][h])



Fixed submission:
import sys
import math
import functools
stdin = sys.stdin
mod = 10**9 + 7

ns = lambda: stdin.readline().rstrip()
ni = lambda: int(ns())
na = lambda: list(map(int, stdin.readline().split()))
sa = lambda h: [list(map(int, stdin.readline().split())) for i in range(h)]

h, n = na()
a, b = [], []
for _ in range(n):
    ai, bi = na()
    a.append(ai)
    b.append(bi)
inf = 10**9
dp = [[inf]* (10**4+1) for _ in range(n+1)]
for i in range(n):
    for j in range(1, 10**4+1):
        if j < a[i]:
            dp[i+1][j] = min(dp[i][j],((j-1)//a[i]+1)*b[i])
        else:
            dp[i+1][j] = min(dp[i][j],((j-1)//a[i]+1)*b[i], dp[i+1][j - a[i]] + b[i])
print(dp[n][h])

Buggy python submission (verdict: Runtime Error):
import sys
import math
import functools
stdin = sys.stdin
mod = 10**9 + 7

ns = lambda: stdin.readline().rstrip()
ni = lambda: int(ns())
na = lambda: list(map(int, stdin.readline().split()))
sa = lambda h: [list(map(int, stdin.readline().split())) for i in range(h)]

h, n = na()
a, b = [], []
for _ in range(n):
    ai, bi = na()
    a.append(ai)
    b.append(bi)
inf = 10**9
dp = [[inf]* (10**3+1) for _ in range(n+1)]
for i in range(n):
    for j in range(1, 10**4+1):
        if j < a[i]:
            dp[i+1][j] = min(dp[i][j],((j-1)//a[i]+1)*b[i])
        else:
            dp[i+1][j] = min(dp[i][j],((j-1)//a[i]+1)*b[i], dp[i+1][j - a[i]] + b[i])
print(dp[n][h])



Fixed submission:
import sys
import math
import functools
stdin = sys.stdin
mod = 10**9 + 7

ns = lambda: stdin.readline().rstrip()
ni = lambda: int(ns())
na = lambda: list(map(int, stdin.readline().split()))
sa = lambda h: [list(map(int, stdin.readline().split())) for i in range(h)]

h, n = na()
a, b = [], []
for _ in range(n):
    ai, bi = na()
    a.append(ai)
    b.append(bi)
inf = 10**9
dp = [[inf]* (10**4+1) for _ in range(n+1)]
for i in range(n):
    for j in range(1, 10**4+1):
        if j < a[i]:
            dp[i+1][j] = min(dp[i][j],((j-1)//a[i]+1)*b[i])
        else:
            dp[i+1][j] = min(dp[i][j],((j-1)//a[i]+1)*b[i], dp[i+1][j - a[i]] + b[i])
print(dp[n][h])

Buggy python submission (verdict: Runtime Error):
import sys
import math
import functools
stdin = sys.stdin
mod = 10**9 + 7

ns = lambda: stdin.readline().rstrip()
ni = lambda: int(ns())
na = lambda: list(map(int, stdin.readline().split()))
sa = lambda h: [list(map(int, stdin.readline().split())) for i in range(h)]

h, n = na()
a, b = [], []
for _ in range(n):
    ai, bi = na()
    a.append(ai)
    b.append(bi)
inf = 10**9
dp = [[inf]* (10**3+1) for _ in range(n+1)]
for i in range(n):
    for j in range(1, 10**4+1):
        if j < a[i]:
            dp[i+1][j] = min(dp[i][j],((j-1)//a[i]+1)*b[i])
        else:
            dp[i+1][j] = min(dp[i][j],((j-1)//a[i]+1)*b[i], dp[i+1][j - a[i]] + b[i])
print(dp[n][h])



Fixed submission:
import sys
import math
import functools
stdin = sys.stdin
mod = 10**9 + 7

ns = lambda: stdin.readline().rstrip()
ni = lambda: int(ns())
na = lambda: list(map(int, stdin.readline().split()))
sa = lambda h: [list(map(int, stdin.readline().split())) for i in range(h)]

h, n = na()
a, b = [], []
for _ in range(n):
    ai, bi = na()
    a.append(ai)
    b.append(bi)
inf = 10**9
dp = [[inf]* (10**4+1) for _ in range(n+1)]
for i in range(n):
    for j in range(1, 10**4+1):
        if j < a[i]:
            dp[i+1][j] = min(dp[i][j],((j-1)//a[i]+1)*b[i])
        else:
            dp[i+1][j] = min(dp[i][j],((j-1)//a[i]+1)*b[i], dp[i+1][j - a[i]] + b[i])
print(dp[n][h])

Buggy python submission (verdict: Time Limit Exceeded):
import sys
import math
import functools
stdin = sys.stdin
mod = 10**9 + 7

ns = lambda: stdin.readline().rstrip()
ni = lambda: int(ns())
na = lambda: list(map(int, stdin.readline().split()))
sa = lambda h: [list(map(int, stdin.readline().split())) for i in range(h)]

h, n = na()
a, b = [], []
for _ in range(n):
    ai, bi = na()
    a.append(ai)
    b.append(bi)
inf = 10**9
dp = [[inf]* (10**4+1) for _ in range(n+1)]
for i in range(n):
    for j in range(1, 10**4+1):
        if j < a[i]:
            dp[i+1][j] = min(dp[i][j],((j-1)//a[i]+1)*b[i])
        else:
            dp[i+1][j] = min(dp[i][j],((j-1)//a[i]+1)*b[i], dp[i+1][j - a[i]] + b[i])
print(dp[n][h])



Fixed submission:
import sys
import math
import functools
stdin = sys.stdin
mod = 10**9 + 7

ns = lambda: stdin.readline().rstrip()
ni = lambda: int(ns())
na = lambda: list(map(int, stdin.readline().split()))
sa = lambda h: [list(map(int, stdin.readline().split())) for i in range(h)]

h, n = na()
a, b = [], []
for _ in range(n):
    ai, bi = na()
    a.append(ai)
    b.append(bi)
inf = 10**9
dp = [[inf]* (10**4+1) for _ in range(n+1)]
for i in range(n):
    for j in range(1, 10**4+1):
        if j < a[i]:
            dp[i+1][j] = min(dp[i][j],((j-1)//a[i]+1)*b[i])
        else:
            dp[i+1][j] = min(dp[i][j],((j-1)//a[i]+1)*b[i], dp[i+1][j - a[i]] + b[i])
print(dp[n][h])