1 #include 
     
       2 #define _for(i,a,b) for(int i = (a);i < b;i ++) 3 typedef long long ll; 4 using namespace std; 5 int N,m; 6 inline ll read() 7 { 8     ll ans = 0; 9     char ch = getchar(), last = ' ';10     while(!isdigit(ch)) last = ch, ch = getchar();11     while(isdigit(ch)) ans = (ans << 1) + (ans << 3) + ch - '0', ch = getchar();12     if(last == '-') ans = -ans;13     return ans;14 }15 inline void write(ll x)16 {17     if(x < 0) x = -x, putchar('-');18     if(x >= 10) write(x / 10);19     putchar(x % 10 + '0');20 }21 int dp[26][30009];22 int a[2][30];23 int main()24 {25     N = read(),m = read();26     _for(i,1,m+1)27         _for(j,0,2)28             a[j][i] = read(); 29     memset(dp,0,sizeof(dp));30     _for(i,1,m+1)31     {32         _for(j,0,N+1)33         {34             if(a[0][i] <= j)35                 dp[i][j] = max(dp[i-1][j],dp[i-1][j-a[0][i]]+a[0][i]*a[1][i]);36             else37                 dp[i][j] = dp[i-1][j];38         }39     }40     write(dp[m][N]);41     return 0;42 }