// paiza POH! Lite
// result:
// http://p...content-available-to-author-only...a.jp/poh/kirishima/result/fb335efcd282df66a439fb1dc0121293
// author: Leonardone @ NEETSDKASU
process.stdin.resume();
process.stdin.setEncoding('utf8');
process.stdin.on('data', function (chunk) {
var lines = chunk.toString().split('\n');
var m = lines[0] ^ 0;
var n = lines[1] ^ 0;
var w = -m;
var p = 0;
var i,j,line;
for(i=n+1; i>1; i--) {
line = lines[i] = lines[i].split(" ");
w += line[0] ^ 0;
p += line[1] ^ 0;
}
var a = [];
var b = [];
var c = a;
for(j=0; j<=w; j++) {
a[j] = 0;
}
for(i=0; i<n; i++) {
line=lines[i+2];
for(j=0; j<=w; j++) {
if(line[0] <= j) {
var x = a[j];
var y = a[j-line[0]] + (line[1] ^ 0);
b[j] = (x > y) ? x : y;
} else {
b[j] = a[j];
}
}
c = a;
a = b;
b = c;
}
console.log(p - a[w]);
});
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