蓝桥杯-开心的金明

//蓝桥杯-算法训练    开心的金明
//评测结果    AC
//动态规划  01背包

#include <cstdio>
#include <algorithm>
#include <cstring>
using namespace std;

const int maxn = 30005;
int main() {
    int N, m;
    scanf( "%d%d", &N, &m );
    int f[maxn];

    int v, w;
    memset( f, 0, sizeof( f ) );
    for( int i = 1; i <= m; i++ ) {
        scanf( "%d%d", &v, &w );
        for( int j = N; j >= 0; j-- )
            if( j >= v ) f[j] = max( f[j], f[j - v] + w * v );
    }
    printf( "%d", f[N] );
    return 0;
}