#include<bits/stdc++.h>
using namespace std;
const int N=110,M=1e6+10;
int n,m,A[N],B[N]; 
unsigned long long C[M], ans[M];
void calc()
{
    memset(C,0,sizeof(C));for(int i=0;i<=A[1]*B[1];i+=A[1])C[i]=1;
    for(int k=2;k<=n;k++)
    {
        memset(ans,0,sizeof(ans));
        for(int i=0;i<=m;i++)
            for(int j=0;j<=A[k]*B[k] && (i+j<=m);j+=A[k])
                ans[i+j]+=C[i];
        memcpy(C,ans,sizeof(ans));
    }
    int x=0;while(C[x])x++;
    printf("%d\n",x);
}
int main()
{
    scanf("%d",&n);m=0;
    for(int i=1;i<=n;i++)scanf("%d%d", &A[i], &B[i]),m+=B[i]*A[i];
    calc();
    return 0;
}