$dp$

#include<bits/stdc++.h>
using namespace std;
int i,j,n,c,v,ma,k[10005],m[10005],f[10005];
int main()
{
	cin>>v>>n>>c;
	for(i=1;i<=n;i++)cin>>k[i]>>m[i];
	for(i=1;i<=10000;i++)f[i]=1e9;
	for(i=1;i<=n;i++)
		for(j=v;j>=k[i];j--)
			f[j]=min(f[j],f[j-k[i]]+m[i]);
	c-=f[v];
	if(c<0)cout<<"Impossible";
	else cout<<c;
}