// #includes {{{
#include <bits/stdc++.h>
using namespace std;

#define REP(i,n) for(int i=0;i<(int)(n);++i)
#define RREP(i,a,b) for(int i=(int)(a);i<(int)(b);++i)
#define FOR(i,c) for(__typeof((c).begin()) i=(c).begin();i!=(c).end();++i)
#define LET(x,a) __typeof(a) x(a)
//#define IFOR(i,it,c) for(__typeof((c).begin())it=(c).begin();it!=(c).end();++it,++i)
#define ALL(c) (c).begin(), (c).end()
#define MP make_pair

#define EXIST(e,s) ((s).find(e)!=(s).end())

#define RESET(a) memset((a),0,sizeof(a))
#define SET(a) memset((a),-1,sizeof(a))
#define PB push_back
#define DEC(it,command) __typeof(command) it=command

//debug
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;
#define debug_v(x) cerr << #x << " = [";REP(__ind,(x).size()){cerr << (x)[__ind] << ", ";}cerr << "] (L" << __LINE__ << ")" << endl;

#define whole(f,x,...) ([&](decltype((x)) whole) { return (f)(begin(whole), end(whole), ## __VA_ARGS__); })(x)

typedef long long Int;
typedef unsigned long long uInt;
typedef long double rn;

template<class T>
T inf(){
	return numeric_limits<T>::has_infinity?numeric_limits<T>::infinity():(numeric_limits<T>::max()/2);
}

typedef pair<int,int> pii;

/*
#ifdef MYDEBUG
#include"debug.h"
#include"print.h"
#endif
*/
// }}}


//{{{ io
FILE *file_in=stdin,*file_out=stdout;
#define fin normal_in
#define fout normal_out
//const char fname[]="";
//FILE *fin=fopen(fname,"r"),*fout=fopen(fname,"w");
#ifdef __MINGW32__
#define LLD "%I64d"
#define LLU "%I64u"
#else
#define LLD "%lld"
#define LLU "%llu"
#endif
struct NORMAL_IN{
	bool cnt;
	NORMAL_IN():cnt(true){}
	operator int() const {return cnt;}
#define endl "\n"
	NORMAL_IN& operator>>(int &n){cnt=fscanf(file_in,"%d",&n)!=EOF;return *this;}
	NORMAL_IN& operator>>(unsigned int &n){cnt=fscanf(file_in,"%u",&n)!=EOF;return *this;}
	NORMAL_IN& operator>>(long long &n){cnt=fscanf(file_in,LLD,&n)!=EOF;return *this;}
	NORMAL_IN& operator>>(unsigned long long &n){cnt=fscanf(file_in,LLU,&n)!=EOF;return *this;}
	NORMAL_IN& operator>>(double &n){cnt=fscanf(file_in,"%lf",&n)!=EOF;return *this;}
	NORMAL_IN& operator>>(long double &n){cnt=fscanf(file_in,"%Lf",&n)!=EOF;return *this;}
	NORMAL_IN& operator>>(char *c){cnt=fscanf(file_in,"%s",c)!=EOF;return *this;}
	NORMAL_IN& operator>>(string &s){
		s.clear();
		for(bool r=false;;){
			const char c=getchar();
			if(c==EOF){ cnt=false; break;}
			const int t=isspace(c);
			if(!r and !t)r=true;
			if(r){
				if(!t)s.push_back(c);
				else break;
			}
		}
		return *this;
	}
	template<class T>
		NORMAL_IN& operator>>(vector<T> &v){
			int v_size = v.size();
			REP(i,v_size){
				*this>>v[i];
			}
			return *this;
		}
} normal_in;

struct NORMAL_OUT{
	NORMAL_OUT& operator<<(const int &n){fprintf(file_out,"%d",n);return *this;}
	NORMAL_OUT& operator<<(const unsigned int &n){fprintf(file_out,"%u",n);return *this;}
	NORMAL_OUT& operator<<(const long long &n){fprintf(file_out,LLD,n);return *this;}
	NORMAL_OUT& operator<<(const unsigned long long &n){fprintf(file_out,LLU,n);return *this;}
	NORMAL_OUT& operator<<(const double &n){fprintf(file_out,"%lf",n);return *this;}
	NORMAL_OUT& operator<<(const long double &n){fprintf(file_out,"%Lf",n);return *this;}
	NORMAL_OUT& operator<<(const char c[]){fprintf(file_out,"%s",c);return *this;}
	NORMAL_OUT& operator<<(const string &s){fprintf(file_out,"%s",s.c_str());return *this;}
} normal_out;
struct ERR_OUT{
	template<class T>
		ERR_OUT& operator<<(const T &a){
			cerr<<"\x1b[7m"<<a<<"\x1b[m";
			return *this;
		}
} ferr;
//}}}

//{{{ Print functions
// Input/Output
template<class T>
void matrix_out(const vector<vector<T> > &x){
	REP(i,x.size()){
		REP(j,x[0].size()){
			cout<<x[i][j]<<"\t";
		}
		cout<<endl;
	}
}

template<class U,class S,class T>
U &operator<<(U &os, const pair<S,T> &p){
	os<<"("<<p.first<<", "<<p.second<<")";
	return os;
}

void printBit(int b,int k=-1){
	if(k==-1){
		int bb=1,i=0;
		while(bb){
			if(b&bb)k=i;
			bb<<=1;i++;
		}
	}
	REP(ct,k){
		cout<<b%2;
		b>>=1;
	}
	cout<<endl;
}

template<typename U, template <typename... Args> class Container,typename... Types>
U &operator<<(U &os, const Container<Types...> &x) {
	os<<"{";
	for(const auto &e:x)os<<" "<<e<<" ";
	os<<"}";
	return os;
}
//}}}

void solve(Int D, Int G, vector<Int> p, vector<Int> c){
	Int ans = inf<Int>();
	int B = (1<<D);
	REP(b,B){
		Int score = 0, num = 0;
		vector<Int> v;
		REP(i,D){
			if(b&(1<<i))score += p[i]*100*(i+1) + c[i], num+=p[i];
			else{
				REP(j,p[i])v.push_back(100*(i+1));
			}
		}
		reverse(ALL(v));
//		cout<<v<<endl;
		for(int i=0;i<(int)v.size() and score<G;i++){
			score+=v[i];
			num++;
		}
		if(score>=G){
			ans = min(ans,num);
		}
	}
	fout<<ans<<endl;
}

//{{{ main function
int main(){	
	Int G;
	Int D;
	fin >> D;
	vector<Int> p(D-1+1);
	vector<Int> c(D-1+1);
	fin >> G;
	for(int i = 0 ; i <= D-1 ; i++){
		fin >> p[i];
		fin >> c[i];
	}
	solve(D, G, p, c);
	return 0;
}
//}}}


Measured memory_bytes: 256