### BUGGY CODE ###

#3
d,g = map(int,input().split())
lista = []
for i in range(d):
    lista.append([])
    p,c = map(int,input().split())
    lista[i] = [p,c]
    
def search(allcomp,notouch,touch,rem,toachiev,ps):
    #allcomp 全部解く
    #notouch 触らない
    #touch 触る
    #残りの選択肢
    #達成までに必要な得点
    #ここまで解いてる問題数
    if touch != []:
        #print(allcomp,notouch,touch,rem,toachiev,ps)
        point = (touch[0] + 1)*100
        problems = lista[touch[0]][0]
        vnus =  lista[touch[0]][1]
        #print(point,problems,vnus)
        if toachiev == 0:
            return ps
        else:
            needproblems = toachiev//point
            if toachiev%point != 0:
                needproblems += 1
                
            if needproblems<=problems:
                return ps+needproblems
            else:
                if point*problems + vnus >= toachiev:
                    return ps+problems
                else:
                    return 10**9
                
    else:
        if len(rem)==1:
            rempoint = (rem[0] + 1)*100
            notouchpoint_max = 0
            if notouch != []:
                notouchpoint_max = (max(notouch) + 1)*100
            
            if notouchpoint_max <= rempoint:
                return search(allcomp,notouch,rem,[],toachiev,ps)
            else:
                return 10**9
        else:
            minp = 10**9
            for i in range(len(rem)):
                allcomp_t,notouch_t,rem_t,toachiev_t,ps_t = list(allcomp),list(notouch),list(rem),toachiev,ps
                allcomp_t.append(rem[i])
                rem_t = rem[:i]+rem[i+1:]
                toachiev_t = toachiev_t - (rem[i] + 1)*100*lista[rem[i]][0] - lista[rem[i]][1]
                if toachiev_t <0:
                    toachiev_t = 0
                ps_t = ps_t + lista[rem[i]][0]
                case1 = search(allcomp_t,notouch_t,[],rem_t,toachiev_t,ps_t)
                
                allcomp_t,notouch_t,rem_t,toachiev_t,ps_t = list(allcomp),list(notouch),list(rem),toachiev,ps
                notouch_t.append(rem[i])
                rem_t = rem[:i]+rem[i+1:]
                case2 = search(allcomp_t,notouch_t,[],rem_t,toachiev_t,ps_t)
                #print(case1,case2)
                if minp > min(case1,case2):
                    minp = min(case1,case2)
                    
            return minp
                
        
        
        
        
makerem = []
for i in range(d):
    makerem.append(i)
    
print(search([],[],[],makerem,g,0))

### FIXED CODE ###

d,g = map(int,input().split())
p = []
c = []
for i in range(d):
    tp,tc = map(int,input().split())
    p.append(tp)
    c.append(tc)
ans = 1<<50
for i in range(1<<d):#どのコンプリートボーナスを狙うかを決める
    score = 0
    count = 0
    zero_list = []
    for j in range(d):
        if ((i >> j) & 1):
            score += c[j] + p[j]*(j+1)*100 
            count += p[j]
        else:
            zero_list.append(j)
    if score >= g:
        ans = min(ans,count)
    else:#もしまだ点数が届いていないならボーナスを狙わないものから点数が高い問題を解く
        rem = g-score
        if rem <= (p[max(zero_list)]-1)*(max(zero_list)+1)*100:
            for i in range(1,p[max(zero_list)]):
                if rem - i*(max(zero_list)+1)*100 <= 0:
                    count +=  i
                    ans = min(ans,count)
                    break
print(ans)