codeforces #326 div 2 A. Duff and Meat(水）

A. Duff and Meat

time limit per test
1 second

memory limit per test
256 megabytes

input
standard input

output
standard output

Duff is addicted to meat! Malek wants to keep her happy for n days. In order to be happy in i-th day, she needs to eat exactly ai kilograms of meat.

/*************************************************************************
> File Name: code/cf/#326/A.cpp
> Author: 111qqz
> Email: rkz2013@126.com
> Created Time: 2015年10月22日 星期四 20时00分33秒
************************************************************************/

#include<iostream>
#include<iomanip>
#include<cstdio>
#include<algorithm>
#include<cmath>
#include<cstring>
#include<string>
#include<map>
#include<set>
#include<queue>
#include<vector>
#include<stack>
#include<cctype>

#define yn hez111qqz
#define j1 cute111qqz
#define ms(a,x) memset(a,x,sizeof(a))
using namespace std;
const int dx4[4]={1,0,0,-1};
const int dy4[4]={0,-1,1,0};
typedef long long LL;
typedef double DB;
const int inf = 0x3f3f3f3f;
const int N=1E5+7;
int n;
int a
,p
;
int main()
{
#ifndef  ONLINE_JUDGE
freopen("in.txt","r",stdin);
#endif

scanf("%d",&n);
for ( int i = 0 ;  i < n ; i++) scanf("%d %d",&a[i],&p[i]);
int mi = inf;
int ans = 0 ;
for ( int i = 0 ; i < n ; i++)
{
if (p[i]<mi)
mi = p[i];

ans += mi*a[i];
}
cout<<ans<<endl;

#ifndef ONLINE_JUDGE
fclose(stdin);
#endif
return 0;
}

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