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#!/usr/bin/env python3

import sys


def main():
    N, M, S = [int(x) for x in input().split()]
    rawlrs = []
    for i in range(M):
        rawlrs.append([int(x) for x in input().split()])
    rawlrs.sort()

    lrs = []
    xl, xr = rawlrs[0]
    for l, r in rawlrs[1:]:
        if xr + 1 == l:
            xr = r
        else:
            lrs.append([xl, xr])
            xl, xr = l, r
    lrs.append([xl, xr])

    d = N
    p = 0
    for l, r in lrs:
        if l <= S:
            if r < S:
                if d > (di := S - (r + 1)):
                    d = di
                    p = r + 1
            else:
                ll, rr = l - 1, r + 1
                if ll >= 1 and d > (di := S - ll):
                    d = di
                    p = ll
                if rr <= N and d > (di := rr - S):
                    d = di
                    p = rr
                break
        else:
            if d > (di := (l - 1) - S):
                d = di
                p = l - 1
            break

    print(p)


if __name__ == "__main__":
    if len(sys.argv) == 2:
        sys.stdin = open(sys.argv[1])
    main()