var GET=(function(){function f(s){return new g(s);}function g(s){this._s=s.trim().split("\n");this._y=0;}g.prototype.a=function(f){var s=this._s, y=this._y, r;if(typeof s[y]==="string")s[y]=s[y].split(" ").reverse();r=s[y].pop();if(!s[y].length)this._y++;return f?r:+r;};g.prototype.l=function(f){var s=this._s[this._y++].split(" ");return f?s:s.map(a=>+a);};g.prototype.m=function(n,f){var r=this._s.slice(this._y,this._y+=n).map(a=>a.split(" "));return f?r:r.map(a=>a.map(a=>+a));};g.prototype.r=function(n,f){var r=this._s.slice(this._y,this._y+=n);return f?r:r.map(a=>+a);};return f;})();
var o=GET(require("fs").readFileSync("/dev/stdin","utf8"));
function xArray(v){var a=arguments,l=a.length,r="Array(a["+--l+"]).fill(v)";while(--l)r="Array(a["+l+"]).fill(0).map(x=>"+r+")";return eval(r);}

console.log(main());
function main(){
  var n = o.a();
  var q = o.a();
  var s = o.a(1);
  var d = o.m(q,1);
  var ok = n, ng = -1;
  var ans = n;
  while(ok-ng > 1){
    var m = ok+ng >> 1;
    var t = m;
    for(var i = 0; i < q; i++){
      if(s[t] === d[i][0]){
        if(d[i][1] === "L"){
          if(t === 0){
            ng = m;
            break;
          }
          t--;
        }
        else{
          if(t === n-1){
            break;
          }
          t++;
        }
      }
    }
    if(ng !== m)ok = m;
  }
  ans -= ok;
  ok = -1; ng = n;
  while(ng-ok > 1){
    var m = ok+ng >> 1;
    var t = m;
    for(var i = 0; i < q; i++){
      if(s[t] === d[i][0]){
        if(d[i][1] === "L"){
          if(t === 0){
            break;
          }
          t--;
        }
        else{
          if(t === n-1){
            ng = m;
            break;
          }
          t++;
        }
      }
    }
    if(ng !== m)ok = m;
  }
  ans += ok - n + 1;
  return ans;
}