import std.stdio, std.conv, std.string, std.array, std.range, std.algorithm, std.container;
import std.math, std.random, std.bigint, std.datetime, std.format;
void main(string[] args){ if(args.length > 1) if(args[1] == "-debug") DEBUG = 1; solve(); }
void log()(){ writeln(""); } void log(T, A ...)(T t, lazy A a){ if(DEBUG) write(t, " "), log(a); } bool DEBUG = 0; 
string read(){ static string[] ss; while(!ss.length) ss = readln.chomp.split; string res = ss[0]; ss.popFront; return res; }
// ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- //

void solve(){
	
	int l = read.to!int;
	
	long infty = 1L<<32;
	
	long[] depths = [1];
	long ans;
	foreach(_; 0 .. l){
		
		string cmd = read;
		if(cmd == "for"){
			long val = read.to!long;
			long d = depths[$ - 1] * val;
			if(d >= infty) d = infty;
			
			depths ~= d;
		}
		else if(cmd == "add"){
			long d = depths[$ - 1];
			ans += d;
			if(ans >= infty){
				"OVERFLOW!!!".writeln;
				return;
			}
		}
		else if(cmd == "end"){
			depths.length -= 1;
		}
		
	}
	ans.writeln;
}
