Buggy python submission (verdict: Runtime Error):
inf = 10**9
H, N = map(int, input().split())
AB = [[0, 0] for i in range(N)]
for i in range(N):
    AB[i][0], AB[i][1] = map(int, input().split())
AB.sort()
T = [[inf for i in range(H+1)] for j in range(N)]
for i in range(N):
    T[i][0] = 0
    if i == 0:
        for j in range(1, H+1):
            if j % AB[i][0] > 0:
                T[i][j] = AB[0][1] * (j // AB[0][0] + 1)
            else:
                T[i][j] = AB[0][1] * (j // AB[0][0])
    else:
        for j in range(1, AB[i][0]):
            T[i][j] = min(T[i-1][j], AB[i][1])
        for j in range(AB[i][0], H+1):
            T[i][j] = min(T[i-1][j], T[i][j - AB[i][0]]+AB[i][1])
print(T[N-1][H])

Fixed submission:
inf = 10**9
H, N = map(int, input().split())
AB = [[0, 0] for i in range(N)]
for i in range(N):
    AB[i][0], AB[i][1] = map(int, input().split())
AB.sort()
T = [[inf for i in range(H+1)] for j in range(N)]
for i in range(N):
    T[i][0] = 0
    if i == 0:
        for j in range(1, H+1):
            if j % AB[i][0] > 0:
                T[i][j] = AB[0][1] * (j // AB[0][0] + 1)
            else:
                T[i][j] = AB[0][1] * (j // AB[0][0])
    else:
        for j in range(1, min(AB[i][0], H+1)):
            T[i][j] = min(T[i-1][j], AB[i][1])
        for j in range(AB[i][0], H+1):
            T[i][j] = min(T[i-1][j], T[i][j - AB[i][0]]+AB[i][1])
print(T[N-1][H])

Buggy python submission (verdict: Runtime Error):
inf = 10**9
H, N = map(int, input().split())
AB = [[0, 0] for i in range(N)]
for i in range(N):
    AB[i][0], AB[i][1] = map(int, input().split())
AB.sort()
T = [[inf for i in range(H+1)] for j in range(N)]
for i in range(N):
    T[i][0] = 0
    if i == 0:
        for j in range(1, H+1):
            if j % AB[i][0] > 0:
                T[i][j] = AB[0][1] * (j // AB[0][0] + 1)
            else:
                T[i][j] = AB[0][1] * (j // AB[0][0])
    else:
        for j in range(1, AB[i][0]):
            T[i][j] = T[i-1][j]
        for j in range(AB[i][0], H+1):
            T[i][j] = min(T[i-1][j], T[i][j - AB[i][0]]+AB[i][1])
print(T[-1][-1])

Fixed submission:
inf = 10**9
H, N = map(int, input().split())
AB = [[0, 0] for i in range(N)]
for i in range(N):
    AB[i][0], AB[i][1] = map(int, input().split())
AB.sort()
T = [[inf for i in range(H+1)] for j in range(N)]
for i in range(N):
    T[i][0] = 0
    if i == 0:
        for j in range(1, H+1):
            if j % AB[i][0] > 0:
                T[i][j] = AB[0][1] * (j // AB[0][0] + 1)
            else:
                T[i][j] = AB[0][1] * (j // AB[0][0])
    else:
        for j in range(1, min(AB[i][0], H+1)):
            T[i][j] = min(T[i-1][j], AB[i][1])
        for j in range(AB[i][0], H+1):
            T[i][j] = min(T[i-1][j], T[i][j - AB[i][0]]+AB[i][1])
print(T[N-1][H])

Buggy python submission (verdict: Runtime Error):
inf = 10**9
H, N = map(int, input().split())
AB = [[0, 0] for i in range(N)]
for i in range(N):
    AB[i][0], AB[i][1] = map(int, input().split())
AB.sort()
T = [[inf for i in range(H+1)] for j in range(N)]
for i in range(N):
    T[i][0] = 0
    if i == 0:
        for j in range(1, H+1):
            if j % AB[i][0] > 0:
                T[i][j] = AB[0][1] * (j // AB[0][0] + 1)
            else:
                T[i][j] = AB[0][1] * (j // AB[0][0])
    else:
        for j in range(1, H+1):
            T[i][j] = min(T[i-1][j], T[i][j - AB[i][0]]+AB[i][1])
print(T[-1][-1])

Fixed submission:
inf = 10**9
H, N = map(int, input().split())
AB = [[0, 0] for i in range(N)]
for i in range(N):
    AB[i][0], AB[i][1] = map(int, input().split())
AB.sort()
T = [[inf for i in range(H+1)] for j in range(N)]
for i in range(N):
    T[i][0] = 0
    if i == 0:
        for j in range(1, H+1):
            if j % AB[i][0] > 0:
                T[i][j] = AB[0][1] * (j // AB[0][0] + 1)
            else:
                T[i][j] = AB[0][1] * (j // AB[0][0])
    else:
        for j in range(1, min(AB[i][0], H+1)):
            T[i][j] = min(T[i-1][j], AB[i][1])
        for j in range(AB[i][0], H+1):
            T[i][j] = min(T[i-1][j], T[i][j - AB[i][0]]+AB[i][1])
print(T[N-1][H])