var regs = {};
var lines = require("fs").readFileSync("input.txt").toString().split("\n").filter((a)=>(a));
getreg = (reg)=>((reg in regs) ? (regs[reg]) : (0));
var max = 0;
for(var line of lines){
	var condition = new RegExp("[a-z]+ (inc|dec) (-?)[0-9]+ if (.*)").exec(line)[3].replace(/^([a-z]+) (.*)/, "getreg('$1') $2");
	if(eval(condition)){
		if(!(line.split(" ")[0] in regs)){
			regs[line.split(" ")[0]] = 0;
		}
		regs[line.split(" ")[0]] += ((line.split(" ")[1] == "inc") ? 1 : -1) * parseInt(line.split(" ")[2]);
		if(regs[line.split(" ")[0]] > max){
			max = regs[line.split(" ")[0]];
		}
	}
}
console.log(max);