import core.bitop, std.algorithm, std.ascii, std.bigint, std.conv, std.math,
    std.functional, std.numeric, std.range, std.stdio, std.string, std.random,
    std.typecons, std.container;

// dfmt off
T lread(T = long)(){return readln.chomp.to!T();}
T[] aryread(T = long)(){return readln.split.to!(T[])();}
void scan(TList...)(ref TList Args){auto line = readln.split();
foreach (i, T; TList){T val = line[i].to!(T);Args[i] = val;}}
alias sread = () => readln.chomp();enum MOD = 10 ^^ 9 + 7;
// dfmt on

void main()
{
    long N, M;
    scan(N, M);
    auto A = aryread();
    auto B = new long[M];
    auto C = new long[M];
    foreach (i; 0 .. M)
        scan(B[i], C[i]);

    A.sort();
    zip(C, B).sort!"b<a"();

    long sum = A.sum();
    long ans = sum;
    long i, j;
    foreach (x; 0 .. N)
    {
        if (B[i] == j)
        {
            j = 0;
            i++;
        }
        if (B.length <= i)
            break;
        sum -= A[x];
        sum += C[i];
        ans = max(ans, sum);
        j++;
    }
    writeln(ans);
}
