public int strToInt(String str) {
		int i=0;
		int num = 0;
		boolean isNeg = false;

		if(str.charAt(0)=='-') {
			isNeg=true;
			i=1;
		}

		while (i<str.length()) {
			num *=10;
			num += str.charAt(i++) -'0';
		}

		if(isNeg)
			num = -num;

		return num;

	}