C++ :

#include<iostream>
#include<algorithm>
#include<cstdio>
using namespace std;
const int N(1005);
int w[N],v[N];
double f[N];
int main()
{
//	freopen("convoy.in","r",stdin);
//	freopen("convoy.out","w",stdout);
	int W,s,n;
	scanf("%d%d%d",&W,&s,&n);  //cin>>W>>s>>n;
	w[0]=0;
	for (int i=1;i<=n;i++)
	{	
		scanf("%d%d",&w[i],&v[i]);  //cin>>w[i]>>v[i];
		w[i]+=w[i-1];
	}
	fill(f+1,f+n+1,0x7fffffff);
	f[0]=0;
	for (int i=1;i<=n;i++)	
		for (int j=1,minv=v[i];j<=i&&w[i]-w[i-j]<=W;j++)
			f[i]=min(f[i],f[i-j]+s/(double)(minv=min(minv,v[i-j+1])));
	printf("%.1lf\n",f[n]*60);
//	system("pause");
	return 0;
}