#include<bits/stdc++.h>
#define sqr(x) ((x)*(x))
#define ll long long
#define ull unsigned long long
#define ui unsigned int
#define ld long double
#define vi vector<int>
#define HEAP(...) priority_queue<__VA_ARGS__ >
#define heap(...) priority_queue<__VA_ARGS__,vector<__VA_ARGS__ >,greater<__VA_ARGS__ > > 
#define pii pair<int,int> 
#define pb push_back
#define mp make_pair
#define debuge cerr<<"isok"<<endl
#define debug(x) cerr<<#x<<"="<<x<<endl
#define dprintf(...) fprintf(stderr,__VA_ARGS__)
#define SS second
#define FF first
#define ls (k<<1)
#define rs (k<<1|1)
#define clr(a,x) memset(a,x,sizeof(a))
#define cpy(a,x) memcpy(a,x,sizeof(a))
#define file(x) freopen(x".in","r",stdin),freopen(x".out","w",stdout)
#define SZ(x) ((int)x.size())
using namespace std;
template<class T> inline void gmin(T &x,const T &y){if(x>y) x=y;}
template<class T> inline void gmax(T &x,const T &y){if(x<y) x=y;}
const int BufferSize=1<<16;
char buffer[BufferSize],*Bufferhead,*Buffertail;
bool Terminal;
inline char Getchar(){
	if(Bufferhead==Buffertail){
		int l=fread(buffer,1,BufferSize,stdin);
		if(!l){Terminal=1;return 0;}
		Buffertail=(Bufferhead=buffer)+l;
	}
	return *Bufferhead++;
}
template<class T>inline bool read(T &x){
	x=0;char c=Getchar(),rev=0;
	while(c<'0'||c>'9'){c=Getchar();rev|=c=='-';if(Terminal)return 0;}
	while(c>='0'&&c<='9') x=x*10+c-'0',c=Getchar();
	if(c=='.'){
		c=Getchar();double t=0.1;
		while(c>='0'&&c<='9') x=x+(c-'0')*t,c=Getchar(),t=t/10;
	}
	x=rev?-x:x;
	return 1;
}
template<class T1,class T2> inline bool read(T1 &x,T2 &y){return read(x)&read(y);}
template<class T1,class T2,class T3> inline bool read(T1 &x,T2 &y,T3 &z){return read(x)&read(y)&read(z);}
template<class T1,class T2,class T3,class T4> inline bool read(T1 &x,T2 &y,T3 &z,T4 &w){return read(x)&read(y)&read(z)&read(w);}
inline bool reads(char *x){
	char c=Getchar();
	while(c<33||c>126){c=Getchar();if(Terminal)return 0;}
	while(c>=33&&c<=126) (*x++)=c,c=Getchar();
	*x=0;return 1;
}
template<class T>inline void print(T x,const char c='\n'){
	if(!x){putchar('0');putchar(c);return;}
	if(x<0) putchar('-'),x=-x;
	int m=0,a[20];
	while(x) a[m++]=x%10,x/=10;
	while(m--) putchar(a[m]+'0');
	putchar(c);
}
//--------------------------------------------------head--------------------------------------------------

const int inf=0x3f3f3f3f;
const int N=1000005,M=100005,mod=998244353;
template<class T,class S> inline void ch(T &x,const S y){x=(x+y)%mod;}
inline int exp(int x,int y,const int mod=::mod){
	int ans=1;
	while(y){
		if(y&1) ans=(ll)ans*x%mod;
		x=(ll)x*x%mod;y>>=1;
	}return ans;
}

int n,m,fac[N],ifac[N];

int main(){
#ifdef rqgao2014
	freopen("input.txt","r",stdin);
#endif
	n=1000000;fac[0]=1;
	for(int i=1;i<=n;i++) fac[i]=(ll)fac[i-1]*i%mod;
	ifac[n]=exp(fac[n],mod-2);
	for(int i=n;i;i--) ifac[i-1]=(ll)ifac[i]*i%mod;
	read(n,m);
	int ans=0;
	for(int i=1;i<=min(n,m);i++)
		ch(ans,(ll)ifac[i]*ifac[i]%mod*ifac[n-i]%mod*ifac[m-i]%mod*fac[i*2-1]%mod*fac[n+m-2*i]%mod*i);
	ans=(ll)ans*fac[n]%mod*fac[m]%mod*ifac[n+m]%mod;
	ch(ans,max(n,m));
	print(ans);
	return 0;
}
#include <bits/stdc++.h>
#include <vector>
using namespace std;
using ll = long long;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep1(j, m) for (int j = 0; j <= (int)(m); j++)

int main()
{
    int d;
    ll g;
    vector<ll> p, c;
    cin >> d >> g;
    p.resize(d);
    c.resize(d);
    rep(i, d)
    {
        cin >> p[i] >> c[i];
    }
    ll res = 1 << 29;
    for (int bit = 0; bit < (1 << d); ++bit)
    {
        ll sum = 0;
        ll num = 0;

        rep(i, d)
        {
            if (bit & (1 << i))
            {
                sum += c[i] + p[i] * 100 * (i + 1);
                num += p[i];
            }
        }
        if (sum >= g)
        {
            res = min(res, num);
        }
        else
        {
            for (int i = d - 1; i >= 0; i--)
            {
                if (bit & (1 << i))
                {
                    continue;
                }
                rep(j, p[i])
                {
                    if (sum >= g)
                    {
                        break;
                    }
                    sum += 100 * (i+1);
                    num++;
                } 
            }
            res = min(res, num);
        }
    }
    cout << res << endl;
}