Petr stands in line of n people, but he doesn't know exactly which position he occupies. He can say that there are no less than a people standing in front of him and no more than b people standing behind him. Find the number of different positions Petr can occupy.

Input

The only line contains three integers n, a and b (0 ≤ a, b < n ≤ 100).

Output

Print the single number — the number of the sought positions.

Examples

Input

3 1 1


Output

2


Input

5 2 3


Output

3

Note

The possible positions in the first sample are: 2 and 3 (if we number the positions starting with 1).

In the second sample they are 3, 4 and 5.
function foo(x) {
    return x * x;
}
function read_int() {
    return readline().split(" ").map(function (x) { return parseInt(x); });
}
function read_float() {
    return readline().split(" ").map(function (x) { return parseFloat(x); });
}
var n = read_int();
var a = n[1];
var b = n[2];
var i, tmp1, tmp2;
var ans = 0;
for (i = 1; i <= n[0]; i++) {
    tmp1 = i - 1;
    tmp2 = n[0] - i;
    if (tmp1 >= a && tmp2 <= b) {
        ans++;
    }
}
print(ans);
