#include<bits/stdc++.h>
#define ll long long
using namespace std;
struct bag
{
	int v=0;
	int h=0;
};
int main()
{
	ios::sync_with_stdio(false);//快速输入
	ll dp[1005][10005]={0},v,n,c;
	bag b[1005];
	cin>>v>>n>>c;
	for(int i=1;i<=n;i++)
	{
		cin>>b[i].v>>b[i].h;
	}
	for(int i=1;i<=n;i++)
	{
		for(int j=0;j<=c;j++)
		{
			if(j<b[i].h)
			{
				dp[i][j]=dp[i-1][j];
			}
			else
			{
				dp[i][j]=max(dp[i-1][j-b[i].h],dp[i-1][j-b[i].h])+b[i].v;
			}
		}
	}
	ll ans=INT_MAX;
	if(dp[n][c]<v)
	{
		cout<<"Impossible\n";
	}
	else
	{
		for(int i=1;i<=n;i++)
		{
			for(int j=0;j<=c;j++)
			{
				if(dp[i][j]-v>=0 ) ans=min(dp[i][j]-v,ans);
			}
		}
		cout<<ans;
	}
	return 0;
}