function main(input) {
  const n = Number(input[0]);
  const arr = input[1].split(" ");
	const cnt = [];
	let now = 0;
	for(let i=n-2; i>=0; i--) {
		if(arr[i+1] !== arr[i]) now++;
		else now = 1;
		cnt[i] = now;
	}
	let ans = 0;
	for(let i=0; i<n-1; i++) {
		if(arr[i] === "1") ans += cnt[i];
	}
	console.log(ans);
}

main(require("fs").readFileSync("/dev/stdin", "utf8").split("\n"));